Itsfantasyy :
So i have this laptop that i dont use anymore and it has a genuine copy of 8.1 (Atleast i assume so) and i wanted to know if i can transfer that OS to my main pc which runs a not so genuine copy of win7 in order to get the free upgrade to windows 10 and not have to deal with it being labeled as an illegitimate copy.
No, you may not move it. OEM versions of Windows (such as yours) are tied to the motherboard it was initially installed on. Even more so with laptops. You cannot use your laptop's Windows key for any system other than your laptop.
If you want a legitimate version of Windows 10 on your desktop, you will need to legitimately purchase it.
-Wolf sends