Re-activating Windows 10 after motherboard change.

You will need a new Windows 10 license:

Previously called Digital Entitlement, when a computer is upgraded from a previous version of Windows; it receives a unique signature of the computer, which is stored on Microsoft Activation Servers. The Windows 7 or Windows 8 genuine license your system was previously running is exchanged for a diagnostics key.

With Digital License, there is no need to know your product key or purchase another product key if you lose it. Anytime you need to reinstall Windows 10 on the same computer, just proceed to do so using any of the available options. Windows 10 will automatically reactivate without asking questions. The only exceptions where the license will be invalidated is dependent on the product channel. If you were previously running an OEM Windows 10, Windows 7 or Windows 8 license; then changing the motherboard will cause the Digital License to no longer work. This will require purchasing a new license. Transferring licenses upgraded from Windows 8 or Windows 7 under the Windows 10 free upgrade is also not allowed under Digital License.

Source: http://www.groovypost.com/how-to-use-digital-license-to-manage-and-activate-windows-10-anniversary-update-licenses/

Hi,

You might find this helpful.

Source: Using the Activation Troubleshooter

Note: The Troubleshoot option is available only if your copy of Windows 10 (Version 1607 or later) isn't activated.

If you recently made a significant hardware change to your device, such as replacing the motherboard, Windows might no longer be activated on your device.

If you linked your Microsoft account to your Windows 10 digital license on the device BEFORE you make the hardware change, you can reactivate Windows using your sign in info:

1. In the troubleshooter, select I changed hardware on this device recently, and then select Next.
2. Enter your Microsoft account and password, and then select Sign in. You’ll also need to enter the password for your local account if the Microsoft account you entered isn’t a connected account.
3. From the list of devices that are linked to your Microsoft account, select the device that you’re currently using, select the check box next to This is the device I’m using right now, and then select Activate.

If you don’t see the device you’re using in the list of results, make sure that you’re signed in using the same Microsoft account you linked to the Windows 10 digital license on your device.

If you’re signed in using the correct Microsoft account, here are some additional reasons why you can’t reactivate Windows:

• The edition of Windows on your device doesn’t match the edition of Windows you linked to your digital license.
• The type of device you’re activating doesn’t match the type of device you linked to your digital license.
• Windows was never activated on your device.
• You reached the limit on the number of times you can reactivate Windows on your device.
• Your device has more than one administrator, and a different administrator already reactivated Windows.
• Your device is managed by your organization and the option to reactivate Windows isn’t available. For help with reactivation, contact your organization’s support person.

If you need additional help reactivating Windows on your device, contact customer support. 

For more info about how to add your Microsoft account and link it to your Windows 10 digital license, see Reactivating Windows 10 after a hardware change.

When I upgrade a preinstalled (OEM) or retail version of Windows 7 or Windows 8/8.1 license to Windows 10, does that license remain OEM or become a retail license?

If you upgrade from a OEM or retail version of Windows 7 or Windows 8/8.1 to the free Windows 10 upgrade this summer, the license is consumed into it. Because the free upgrade is derived from the base qualifying license, Windows 10 will carry that licensing too.

If you upgrade from a retail version, it carries the rights of a retail version.

If you upgrade from a OEM version, it carries the rights of a OEM version.

Full version (Retail):

- Includes transfer rights to another computer.

- Doesn't require a previous qualifying version of Windows.

- Expensive

Upgrade version (Retail):