Come to think of it Windows licensing isn't tied to your email address rather to your hardware(OEM/OTS). Literally every CPU that needs genuine windows needs to have a paid license even if you just bought two machines in 2 years, such a fucking joke.
If you buy windows that isn't OEM the keys are now bound to your email address (more accurately your Microsoft account) those version of windows are easily transportable between hardware.
People often make the mistake of purchasing OEM windows because of the reduced cost but fail to realize they are hardware bound at registration.