Microsoft distributes its software through three main channels: retail, OEM (preinstalled by the PC manufacturer) and volume licensing. Each channel has its own kind of key. The type decides how you install, how you activate and what happens if you change computers.
Retail keys
A retail key belongs to one copy of the product. You enter it during or after installation and activate with Microsoft, usually online. Telephone activation is also available, except for editions such as Windows 11 Pro EDU and Pro for Workstations, which must activate online. Retail licences can be transferred between devices.
How a retail key is used depends on the product:
- Windows 11: you install Windows from Microsoft's download page and enter the key in Settings > System > Activation > Change product key.
- Office (for example Office Home & Business 2024): you redeem the key at office.com/setup. That links Office to your Microsoft account, and you install it from there.
Volume keys (MAK)
MAK stands for Multiple Activation Key. It comes from Microsoft's volume licensing, which is meant for organisations. In Microsoft's words, a MAK acts like a retail key, except that it is valid for activating multiple computers. Each MAK can be used a specific number of times, and every activation counts toward that limit.
Once activated, a MAK activation lasts: Microsoft calls MAK activation perpetual for Windows, and volume Office does not need reactivation unless the hardware changes significantly.
Volume Office is installed differently from retail Office. It comes with a preinstalled generic volume licence key; to activate with a MAK, you replace it with your MAK. For Office LTSC, for example Office LTSC Professional Plus 2024, the Download software button in your key email opens My Library, where the delivery card shows how to get the software.
Details on the limit are in How MAK activation limits work.
OEM licences
For Windows, OEM licences come with a new PC. The manufacturer activates Windows at the factory by linking it to the computer's firmware. Microsoft states that this activation is valid as long as the manufacturer's image stays on that system, and that it exists only for PCs bought with Windows preinstalled. A Windows OEM licence is tied to that one device.
How to tell which key you have
- Before ordering: the product page names the licence type of each option.
- After ordering: check the licence type of the option you ordered on the product page. The buttons in My Library show how the software is delivered, not the licence type.
- On a PC with Windows: open Command Prompt and run the command below. The "Description" line names the channel, for example RETAIL or VOLUME_MAK.
slmgr /dlv
- In volume Office: open Command Prompt as administrator and run the command below. It lists the installed Office licences and their status.
cscript "C:\Program Files\Microsoft Office\root\Office16\OSPP.VBS" /dstatus
If the script is not found there, check C:\Program Files\Microsoft Office\Office16; earlier Office versions may not use the root folder.
Why the type matters
- Activation: retail Office activates through the Microsoft account you redeemed it with. For volume Office, you replace the preinstalled generic key with the MAK you received.
- Moving to a new PC: a retail licence can be transferred and an OEM licence stays with its device. With a MAK, each activation counts toward the limit; how many devices you may use is set in the product description. See Moving a licence to a new PC.
- Reinstalling retail Office: sign in to the Microsoft account you used at office.com/setup and install from Services & subscriptions.
If something goes wrong
You cannot tell which type you have. Check the product page of your order. If you are still unsure, contact our support with your order number.
Office says "This product key has already been used". The retail key is already redeemed. Sign in to the Microsoft account you used and install from Services & subscriptions.
0xC004F074: no Key Management Service could be contacted. Volume Windows or Office is still using the generic volume key. Enter your own MAK and activate again. See error 0xC004F074.
