I think he purchased a site and the seller agreed to pass along the owned vb liscence, along with the domain name, db, and any other stuff.
RapFX - what you will need to do is contact the guy that sold you the site. He will need to send an email to
sales@vbulletin.com I believe to have the ownership info changed over to you (assuming the liscence meets vb's criteria for transfership).