Short answer: yes.
You need your own license to run Windows, and most common licences are OEM version, which are tied to the motherboard - meaning it doesn´t matter at all if a harddrive has windows 7 installed on it or not. You´ll want to format the drive before using it as well.
I am wondering why you would buy a used harddrive at all. You´re risking getting a disc with bad/corrupted sectors and it´s hardly worthwhile when a brandnew drive is quite cheap and comes with a warranty.