Activation depends on what type of license you have of Windows 7/8/10.
If Windows 7/8/10 came preinstalled with the computer, that is called an OEM license. For an OEM license, the license dies as soon as Motherboard dies. So essentially it is non-transferable. If that is the case you need to get a new license.
However, this is not same for retail licenses i.e. you purchased the license through Microsoft store. That does carry transfer rights. If that is the case, please see the below steps:
Run the activation troubleshooter on the new device using the below steps:
Go to Settings>Update and security>Activation and run the troubleshooter.
Select I recently changed hardware on this device.
Please note that Activation troubleshooter requires you to have digital license linked to Microsoft Account.
Alternatively, if that does not help, you would have to call Microsoft Support.
Contact Microsoft using the phone numbers below or use the chat support link(weekdays only)
https://support.microsoft.com/en-in/help/405170...
https://partner.support.services.microsoft.com/...
Please let us know if you need any assistance.