What distinguishes an OEM key from a retail key? In the Windows 11 license terms, Microsoft distinguishes two cases. Software that is delivered preinstalled on a device (“OEM” in everyday use) belongs to that device: under these terms it may only be passed on together with it, and the device manufacturer is responsible for support. Software acquired on its own (“retail” in everyday use) may move to another device that belongs to you, and Microsoft provides limited support. According to Microsoft, these transfer rules do not apply to software acquired in Germany; there, Microsoft refers to the applicable law. The activation technology is the same in both cases: a 25-character key.
Quick decision
- You are buying a new PC with Windows. Windows is preinstalled, the key is stored in the device. As a rule, you do not have to enter anything. According to the license terms, the license belongs to this device.
- You are building a PC yourself or equipping a device that has no Windows. You need a license acquired on its own and enter the key during or after installation.
- You change hardware regularly. For software acquired on its own, the license terms allow the move to another device that belongs to you if you remove the software from the old device.
- You are unsure what you have. If the PC came with Windows, the license is preinstalled. If you bought Windows separately and activated it yourself, it was acquired on its own.
OEM stands for Original Equipment Manufacturer, that is, the device manufacturer. The words “OEM” and “retail” do not appear as such in the license terms. They speak of “software preinstalled on a device” and “stand-alone software”. Further terms are explained in the
license glossary.
The differences according to Microsoft
All information comes from the Microsoft Software License Terms for Windows 11 (as of April 2024) and from Microsoft’s help pages.
| Feature | Preinstalled on a device (“OEM”) | Acquired on its own (“retail”) |
|---|---|---|
| Contracting party for the license | Device manufacturer or software installer | Microsoft, if the software was acquired from a retailer |
| Tie to the device | License belongs to the licensed device | For one device; transferable to another device that belongs to you |
| Move to another device that belongs to you | Not provided for | Allowed; the software must be removed from the old device |
| Passing on to another person | Only together with the device, including the Windows label with the key, if there is one | Allowed if you are the first licensee and the new person agrees to the terms |
| Support | Device manufacturer or installer | Microsoft, limited support |
| Where to find the key | Stored in the device, in the packaging or on the Certificate of Authenticity (COA) label | On a card or label inside the box or in the confirmation email |
| Downgrade to an earlier version | Possible with preinstalled Windows Pro, as long as Microsoft supports the earlier version | Not provided for in the terms |
| Simultaneous use on several devices | No | No; a move must not serve to share one license |
According to their own wording, the transfer rules in section 4 of the license terms do not apply if the software was acquired in Germany or in one of the countries listed at aka.ms/transfer. For these cases, Microsoft points out that a transfer to third parties must comply with the applicable law. This guide does not assess what that means in an individual case.
An upgrade inherits the type of license: if you update from a preinstalled version, you keep a preinstalled license; if you update from one acquired on its own, you keep one acquired on its own.
How Windows is activated
Microsoft names two methods of activation. Which one applies depends on how you got Windows.
| How you got Windows | Activation method |
|---|---|
| New PC with Windows | Product key |
| Boxed copy from a retailer | Product key |
| Digital copy from a retailer | Product key |
| Purchase in the Microsoft Store app | Digital license |
| Purchase from the Microsoft Store online | Product key |
| Free upgrade from an earlier Windows version | Digital license |
The product key is a 25-character code in five blocks. The digital license activates Windows without entering a key; it is linked to the hardware and, if you set this up, to your Microsoft account. Activation itself connects the key or the digital license to the device’s hardware. You enter the key under Settings → System → Activation; the steps are shown in
Activate Windows 11.
Hardware replacement and new PC
If you replace essential parts such as the motherboard, Windows, according to Microsoft, no longer finds a license that matches the device. Then the following applies:
- If you linked the digital license to your Microsoft account beforehand, you reactivate Windows with the Activation troubleshooter.
- If Windows was not preinstalled and you activated with a product key, you need the same key again after the replacement.
- For preinstalled Windows, the device manufacturer is your point of contact. Microsoft also refers you to the manufacturer if you can no longer find the key.
The move to a new device is described in
Transfer a Windows license to a new PC. Office has rules of its own, see
Transfer an Office license to another PC.
Typical cases
Laptop with Windows 11 Home preinstalled. According to the license terms, the license belongs to the laptop and is only passed on together with it; for software acquired in Germany, Microsoft refers to the applicable law. If you want Pro features, you buy an upgrade to Pro; the license remains a preinstalled one. The steps:
Upgrade Windows 11 Home to Pro.
Self-built PC. There is no device manufacturer supplying Windows with it. You install Windows from a USB flash drive and activate with a key acquired on its own. Write the key down; after a motherboard replacement you will need it again.
Used company PC with a label. If there is a Certificate of Authenticity label with a key on the device, it belongs to this device. How to display the stored key is explained under
Find your Windows key.
Office with several PCs. The license allows one instance of Windows on one device, so every PC needs its own. Moving from one device to another is not a way to use one license on two devices.
At VivaKeys
Every product page states the product, version and edition, license type, number of devices or users and the type of activation. Read this information before you buy. You can find Windows for the workplace under
Operating systems, for example
Windows 11 Pro. What to look for when choosing is covered under Buying Windows 11 Pro.
Are you unsure which license fits your device?
Ask us before you order. You can find all support dates in the
Microsoft end of support calendar.
Frequently asked questions
What is the difference between a Windows 11 Pro key as OEM and as retail? Both activate Windows 11 Pro with a 25-character key. The difference lies in the license terms: under them, preinstalled software belongs to the device and is supported by the manufacturer, while software acquired on its own may move to another device that belongs to you. According to Microsoft, the transfer rules do not apply to software acquired in Germany; there, Microsoft refers to the applicable law.
Can I transfer a preinstalled Windows license to a new PC? The Windows 11 license terms provide for passing on preinstalled software only together with the licensed device. For software acquired in Germany, Microsoft refers to the applicable law.
Where do I find the product key on a new PC? According to Microsoft, it is stored in the device, included in the packaging or printed on the Certificate of Authenticity label. If you cannot find it, contact the manufacturer.
Do I have to reactivate Windows after a motherboard replacement? Yes. After such a replacement, Windows no longer finds a matching license. With a linked digital license, the Activation troubleshooter helps; otherwise the original product key does.
Who helps with problems with preinstalled Windows? The device manufacturer. That is what the license terms say. For software acquired on its own, Microsoft provides limited support.
Can I use an earlier version with a Windows 11 key? The license terms name downgrade rights only for devices that were delivered with Windows Pro preinstalled, and only for as long as Microsoft supports the earlier version. You have to obtain the earlier version yourself.
Sources
Checked on 2026-11-10 against the publisher’s information:
- www.microsoft.com/content/dam/microsoft/usetm/documents/windows/11/oem-(pre-installed)/UseTerms_OEM_Windows_11_English.pdf
- support.microsoft.com/en-us/windows/activate-windows-c39005d4-95ee-b91e-b399-2820fda32227
- support.microsoft.com/en-us/windows/find-your-windows-product-key-aaa2bf69-7b2b-9f13-f581-a806abf0a886
- support.microsoft.com/en-us/windows/reactivating-windows-after-a-hardware-change-2c0e962a-f04c-145b-6ead-fb3fc72b6665