Re: Reinstall Windows 10. after motherboard replacement
No need to pay anything. Microsoft has instructions here--
If you made a significant hardware change to your device (such as replacing the motherboard), Windows 10 might no longer be activated and you might see the activation error codes 0x803f7001 or 0xC004C008. If you're running Windows 10, version 1607 or later, and added your Microsoft account and linked it to the digital license on your device, you can use the Activation troubleshooter to reactivate Windows.