windows key information

http://www.ghacks.net/2016/09/03/getting-a-windows-product-key-on-the-cheap/

slmgr /dli
to get basic license info
slmgr /xpr
to see if it has an expiration date

http://www.ebay.com/itm/Windows-7-Genuine-Professional-32-64bit-Full-Version-Scrap-PC-License-Key-/172367531959?hash=item2821e7cfb7:g:XJ8AAOSwnHZYjwoZ