Linking Windows Product Key To Your Microsoft Account
Linking your Microsoft account to the product key is very handy should you need to re-activate Windows 10 later on the same computer, because you have reinstalled the Windows, or you have a new computer and needs to migrate your Windows installation on the new computer. Basically it is for backup and safekeeping purpose.
Obviously, you’ll need to have a Microsoft account, you can create one here, if you do not have one yet.
Once you have an account, log into Windows by going to Settings > Update & Security > Activation > click 'Add an account' then sign in to your Microsoft account and you are done.
Once linked, you should now see a message that says 'Windows is activated with a digital license linked to your Microsoft account'.