Set up Windows Server CALs and RD Licensing

A client access licence (CAL) is not software. Microsoft describes it as a licence that gives a user or a device the right to use the services of a server. This guide explains what to do with the CALs from your order: Windows Server CALs only need to be recorded, while RDS CALs need a licence server in your network. Installing the CALs on that server and activating it is covered in Activate RD Licensing and install RDS CALs.

What you received

Your order confirmation email lists the CALs you ordered: type, version and quantity. For RDS CALs it also contains the licence details the Install Licenses wizard asks for: a licence code or an agreement number, depending on the licence programme. The same information is in your Lizensa account under My Library. Keep the email and your invoice. Together they are your proof of licence.

There are two kinds of CAL, and they work very differently.

Windows Server CALs (User CAL or Device CAL). As a rule, every user or device that uses a Windows Server Standard or Datacenter server needs one, for example to open shared files, print or sign in to the domain. Microsoft's Product Terms list a few exceptions. These CALs have no key. You install nothing and activate nothing. Compliance is a matter of having enough CALs and keeping records.

RDS CALs (Remote Desktop Services). Users who work in a remote desktop session on a Remote Desktop session host need an RDS CAL in addition to the Windows Server CAL. RDS CALs are installed on an RD licence server, which issues and tracks them. The details differ between the Per User and Per Device modes. Set this up within the 120-day grace period of a new session host. After that, you need a configured licence server with the right RDS CALs. Per User licensing is not enforced, so working connections do not prove that you hold enough Per User CALs.

Product pages: Windows Server 2025 User CAL, Windows Server 2022 Device CAL, Windows Server 2025 RDS User CAL, Windows Server 2022 RDS Device CAL.

User or device?

• A User CAL covers one person, on any number of devices. It suits staff who work from a laptop, a phone and a home PC.
• A Device CAL covers one device, whoever uses it. It suits shift work, where several people share one PC.

The same choice exists for RDS CALs, as Per User and Per Device. For RDS, each session host uses one licensing mode at a time.

Which version?

A CAL must be the same version as the server it gives access to, or newer. A Windows Server 2022 CAL covers access to Windows Server 2022 and earlier, but not to Windows Server 2025.

For RDS CALs, Microsoft adds a second rule. The RD licence server must run the same version of Windows Server as the RDS CALs, or a newer one. Windows Server 2025 RDS CALs therefore need a licence server on Windows Server 2025.

Windows Server Essentials needs no Windows Server CALs; it is limited to 25 users and 50 devices instead.

Users outside your company

Business partners, contractors or customers who use your server need licences too. Microsoft offers two options: a CAL for each external user, or an External Connector licence for the server, which covers any number of external users. External Connectors are not part of this guide. If you serve many external users, ask our support which option fits.

What you need

There is nothing to download for a CAL. Everything you need is part of Windows Server:

• For Windows Server CALs: a list of users or devices that access your servers.
• For RDS CALs: a Windows Server to act as RD licence server, in the version described above. It can be the same server as the session host or a separate one.
• Administrator rights on that server.
• For a domain: rights to add the licence server to a domain group.

If Windows Server itself is not installed yet, follow Install Windows Server first.

Set up your CALs

Windows Server CALs: keep records

1. Count the users or devices that access each Windows Server, directly or through other software.
2. Compare that number with the CALs you hold, per version.
3. Assign each User CAL to a named person or each Device CAL to a specific device. Record the user or device, the CAL type and version, and the order number, for example in a spreadsheet.
4. Store the order email and invoice with that list. In an audit, they show what you are licensed for.

An example: an office has 12 employees and one shared PC for the warehouse. With User CALs, it needs 12 CALs for the employees plus one for every person who uses only the warehouse PC. With Device CALs, it counts the employees' devices plus the warehouse PC. Choose the model that gives the lower number, and repeat the count whenever staff or devices change.

Windows Server has no key or counter for these CALs. Your records are the proof that you are licensed.

RDS CALs: install the RD Licensing role

1. Sign in to the future licence server with an administrator account.
2. Open Server Manager and select Manage > Add Roles and Features.
3. Select Role-based or feature-based installation, then Next.
4. Select the server from the server pool and select Next.
5. On Server Roles, tick Remote Desktop Services. Select Next until the Role Services page appears.
6. Tick Remote Desktop Licensing. When the wizard asks to add the required features, select Add Features.
7. Select Next until the confirmation page, then Install.

RDS CALs: set the licensing mode on the session hosts

The session hosts must know which licence server to ask and which licensing mode to use. Where you set this depends on your deployment.

With an RD Connection Broker (a full RDS deployment set up in Server Manager):

1. On the Connection Broker, open Server Manager.
2. Go to Remote Desktop Services > Overview > Tasks > Edit Deployment Properties > RD Licensing.
3. Choose Per User or Per Device, matching your RDS CALs.
4. Enter the name of the licence server and select Add, then OK.

Without a Connection Broker (session host and licence server only):

1. Open the Group Policy Management Console for a domain policy, or the Local Group Policy Editor on the session host for a local policy.
2. Go to Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Licensing.
3. Open Use the specified Remote Desktop license servers, select Enabled and enter the licence server name. Separate several servers with commas.
4. Open Set the Remote Desktop licensing mode, select Enabled and choose Per User or Per Device.

In a workgroup without a domain, you must use Per Device. Microsoft does not permit Per User RDS CALs there, because the licence server cannot track users without Active Directory.

Activate the licence server

Windows Server CALs need no activation. For RDS CALs, two steps remain on the licence server:

1. Activate the server once. In Server Manager, open Tools > Remote Desktop Services > Remote Desktop Licensing Manager, select the server and choose Action > Activate Server. With Automatic connection (recommended) and your company details, the server is registered with Microsoft.
2. Install your RDS CALs. The computer running RD Licensing Manager needs internet for this; the licence server itself does not. Right-click the server, select Install Licenses and enter the licence programme, the licence code or agreement number, the product version, the licence type and the quantity from your order.

Both steps in detail, including activation by telephone, are in Activate RD Licensing and install RDS CALs. A new session host has a licensing grace period of 120 days. Finish both steps and the session host settings before that period ends.

In a domain, add the licence server to the Terminal Server License Servers group in Active Directory. RD Licensing Manager offers this under Review Configuration for the server.

Without internet access

If the licence server has no internet access, choose the Telephone connection method in the wizard. Select your country or region, call the number shown and give the details the wizard displays. The Microsoft representative gives you a licence server ID, which you enter in the wizard. Alternatively, activate through a Web Browser on another computer with internet access.

Check the setup

• Windows Server CALs: your list shows at least as many CALs as users or devices, in the right version.
• RDS: on a session host, open Server Manager > Tools and start RD Licensing Diagnoser from the Remote Desktop Services folder. Older Microsoft documentation calls the folder Terminal Services. It shows the licensing mode, the licence server and the number of available licences. A setup without problems shows no warnings at the top.
• For RDS Per User CALs, RD Licensing Manager can create a usage report (not available with Microsoft Entra Domain Services). Right-click the server and select Create Report > CAL Usage.

If something goes wrong

Users see "Remote Desktop licensing mode is not configured". Check that the licensing mode is set and that the session host can reach the licence server you specified. Set both as shown above. Microsoft notes that the message can also appear without a fault, for example when you connect with an administrative session or with a local account in Per User mode.

Connections fail with "there are no Remote Desktop License Servers available to provide a license". The session host cannot obtain a licence. Check that the licence server is activated, that it holds RDS CALs and that the session host points to it. RD Licensing Diagnoser helps you find configuration problems.

RD Licensing Diagnoser shows no available licences although CALs are installed. Check whether the CAL type matches the licensing mode. Per Device CALs do nothing for a host set to Per User, and the reverse. Also check the version: Windows Server 2022 RDS CALs do not serve a session host on Windows Server 2025.

Your RDS CALs do not install on the licence server. Check whether the licence server runs an older Windows Server version than the CALs. It must run the same version or a newer one. If it does not, install RD Licensing on a newer server.

Session hosts in a workgroup cannot reach the licence server. Since a 2024 security update, the licence server requires the session hosts to sign in with real credentials. Microsoft describes storing credentials for the NETWORK SERVICE account with cmdkey on each session host. That step is not needed if both roles run on the same server.

You are unsure how many Windows Server CALs you need. Count everyone who uses the server's services, not only people who sign in at the server. When in doubt, contact our support with your user and device numbers.

Still stuck? Contact our support with your order number, your Windows Server version and a screenshot of RD Licensing Diagnoser.