Can I reuse Windows 10 key OEM on my new motherboard?

The ability to reuse the key depends on what type of license it is and how it was originally sold.

From the description (key in a product envelope, used on a single PC since 2018), it is most likely one of these:

1. OEM (preinstalled / tied to first PC)
   • OEM licenses are normally tied to the first PC (motherboard) they are activated on and cannot be transferred to a new motherboard/PC.
   • When the original motherboard fails and is replaced with a different one, activation can fail with errors like 0xC004F211 or 0xC004F213 because Windows no longer finds a matching license for the new hardware.
   • In this case, the supported path is to purchase a new Windows license for the new PC.
2. Retail (full packaged product)
   • Retail licenses are transferable, but each activation is still checked against Microsoft’s activation rules.
   • After multiple hardware changes, or if the key has already been used on more devices than allowed, activation can fail with errors such as 0xC004F050 (key can’t be used to activate Windows) or 0xC004F211/0xC004F213 (hardware changed / no key found).
   • If activation fails and the Activation troubleshooter cannot resolve it, the guidance is:
     • If Windows came preinstalled on a device and the motherboard was replaced, a new license may be required.
     • Otherwise, use Change product key to enter a valid key, or buy a new product key from the Microsoft Store.

Given the current situation:

• The old devices (motherboards) are broken and one of them has been removed from the Microsoft account.
• The key no longer activates on the new hardware.
• For OEM-type licenses, this is expected and reuse on a new motherboard is not supported.
• For retail-type licenses, if activation and the Activation troubleshooter both fail and the key is reported as unusable, the supported resolution is to purchase a new Windows license/product key for the new PC.

To proceed on the new PC:

1. Open Start > Settings > Update & Security > Activation.
2. Select Change product key and enter the existing key one more time.
   • If this still fails with an error indicating the key cannot be used or no matching license is found, the key cannot be reused in a supported way on this new motherboard.
3. In the same Activation page, select Go to Microsoft Store and purchase a new Windows license/product key, then activate with that new key.

If there is any doubt about whether the key was OEM or retail and the above steps do not work, the remaining supported option is to obtain a new license.

References:

• Why can't I activate Windows?
• Activate Windows
• Windows 10 activation error 0xC004F050
• Get help with Windows activation errors
• Using the Windows Activation troubleshooter
• I cannot find my product key even though I purchased Windows - Microsoft Q&A
• Unable to activate windows after hardware update - Microsoft Q&A
• Unable to use troubleshooter for windows activation - Microsoft Q&A
• Windows reactivation fails - Microsoft Q&A
• Theft/Fraud Associated with my Office Product Key. - Microsoft Q&A