My friend got a free upgrade to windows 10 on his old laptop could i just borrow his Windows key?

[abhishek98]

He his ready to deactivate it from his laptop as he doesn't needs it.
Is there any way it could be any use of mine?

 

[kanewolf]

That isn't "borrowing" it is theft (from Microsoft). That key is associated with that laptop. If you buy his laptop then you get the key, otherwise it is fraudulent use.