How to Activate Windows 11 Pro With an OEM Product Key

Applies to: Windows 11 Pro and Windows 11 Home (upgrading to Pro). The same steps work on Windows 10 with a Windows 10 key, under a different Settings path, which is listed below. Windows 10 reached end of support in October 2025.

Before you start

Three checks save most failed attempts:

• The key matches the edition. A Windows 11 Pro key activates Windows 11 Pro. It does not activate Home, Enterprise, Education or Pro for Workstations. To see what is installed, open Settings > System > About and read Edition under Windows specifications.
• The PC is online. Activation contacts Microsoft’s activation servers. A firewall that blocks them produces error 0xC004FC03.
• You have the full key. It is 25 characters in five groups of five, like XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. Copy and paste it from your order email to avoid mixing up characters such as 8 and B.

You do not need to reinstall Windows to enter a key. If Windows 11 Pro is already installed and shows “Windows is not activated”, go straight to the next section.

How to activate Windows 11 Pro in Settings

This is the method Microsoft documents, and it takes about two minutes.

1. Select Start > Settings > System > Activation.
2. Select Change product key.
3. Enter the 25-character product key.
4. Select Next, then confirm when Windows asks.
5. Wait for the Activation page to refresh. It should now read “Windows is activated with a digital license”.

On Windows 10 the path is Start > Settings > Update & Security > Activation > Change product key. A Windows 11 key and a Windows 10 key are sold as separate products, so use the key that matches the version you installed.

If the PC runs Windows 11 Home

A Pro key entered on Windows 11 Home does two things: it upgrades the edition to Pro, then activates it. Your files and apps stay in place. Microsoft’s instructions are the same four clicks as above: Settings > System > Activation > Change product key, enter the Pro key, select Next.

One condition matters. Microsoft says this route is for a device running an activated copy of Windows Home, and recommends activating Home first if it is not. If Home was never activated on that PC, a clean installation of Pro is the more reliable route.

The differences between the two editions are covered in Windows 11 Home vs Pro.

Enter the key during a clean installation

If you are installing Windows from a USB drive, setup asks for the key on the Activate Windows screen.

1. Start the PC from the Windows 11 installation USB and choose your language and keyboard.
2. On the product key screen, enter the 25-character key. Setup reads the edition from the key and installs Windows 11 Pro.
3. Finish setup and connect to the internet. Windows activates online.

You can also select I don’t have a product key, choose Windows 11 Pro from the edition list, and enter the key later in Settings. Pick the edition carefully: if you install Home here, a Pro key will have to upgrade it afterward.

Laptops and prebuilt PCs: many ship with a Home key stored in the firmware. On those machines setup can skip the edition list and install Home automatically. If that happens, finish setup, let Home activate, then use the Home to Pro steps above.

Activate from the command line

If the Settings page will not accept the key, the built-in licensing script does the same job. Open Command Prompt as administrator and run these two commands, replacing the placeholder with your key:

slmgr.vbs /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
slmgr.vbs /ato

/ipk installs the product key and replaces any key already installed. It returns an error if the key does not apply to the installed edition. /ato asks Windows to try online activation. Each command answers in a small pop-up window after a few seconds.

Check that Windows is activated

Open Settings > System > Activation and read the line next to Activation state. Microsoft lists four possible messages:

For more detail, run either of these in Command Prompt. Neither needs administrator rights.

slmgr.vbs /xpr
slmgr.vbs /dlv

/xpr shows the activation expiration date, or states that the machine is permanently activated. /dlv shows detailed license information, including the license status and the product key channel.

Worth doing now: link the license to a Microsoft account. On the Activation page select Add an account and sign in. Microsoft calls this step essential before a hardware change, because the Activation troubleshooter uses the account to find your license again.

Activation error codes and what they mean

If activation fails, the Activation page shows a code. These are the ones most often seen with a purchased key, with the cause and fix as Microsoft describes them in Get help with Windows activation errors.

Activation troubleshooter: when Windows is not activated, a Troubleshoot button appears on the Activation page. It runs diagnostics and fixes many of these problems on its own. The button is hidden once Windows is activated.

Offline activation: Microsoft’s phone activation line has moved online. If the PC cannot activate over the internet, use offline activation with an Installation ID and Microsoft’s Product Activation Portal. It is not available for Windows 11 Pro Education or Pro for Workstations.

If the key itself was rejected, Windows 11 product key didn’t work goes through each cause in more depth.

After a motherboard change or a reinstall

Reinstalling on the same PC: once Windows is activated, the PC holds a digital license. Reinstall the same edition, select I don’t have a product key if setup asks, and Windows activates online by itself. Keep the key anyway; it is the fallback if that does not happen.

Replacing the motherboard: Windows treats this as a significant hardware change and may no longer find a license that matches the device. Microsoft’s steps to reactivate are:

1. Open Settings > System > Activation and select Troubleshoot.
2. Select I changed hardware on this device recently.
3. Sign in with the Microsoft account you linked to the license.
4. Tick the device you are using and select Activate.

This works only if the license was linked to that account before the change and the edition is the same as before. If Windows was not preinstalled on the PC and you activated it with a key, Microsoft says to enter that same key under Change product key.

What an OEM key does and does not allow

An OEM key installs and activates the same Windows 11 Pro as a retail key: BitLocker, Remote Desktop host, Hyper-V and Group Policy are all included. The difference is in the license terms, and it is worth knowing before you buy.

• It stays with the first PC. An OEM license is tied to the device it is first activated on and is not meant to be moved to a different computer. A retail license can be moved.
• It does not expire. Activation is permanent on that device. You can reinstall Windows on it as often as you need.
• Support comes from the seller. Microsoft directs OEM license questions to the manufacturer or seller. If one of our keys fails to activate, we replace it or refund it.
• One key, one PC. Entering the same key on a second PC leads to error 0xC004C008 or 0xC004C003.

If you still need a key, this is the one we sell: Windows 11 Pro OEM key for 1 PC.