Just to expand a bit on what Maestro said, we've recently been in touch with vBulletin and discovered that no legitimately downloaded vbulletin from their system will ever be without an embedded license #. I used to go by the policy that if you were able to provide said license #, it didn't matter.
However, that last part changed - vBulletin made it quite clear that if the software didn't come from them, they consider it unlicensed. That puts this firmly in the realm of Warez/Copyright Infringement, and results in an immediate and permanent suspension.