Iโll admit that Iโm quite green to these sorts of issues (I wouldnโt ask how an illegal working copy could be possible), however, arenโt there a number of ways to detect stolen and illegal software these days?
If this is something your friend intends to put a good deal of time into, then, a year of usage for vBulletin at the price of $85 or so, doesnโt seem to be too significant to avoid the possible legal action and paranoia that may ensue from such a public action that can, and possibly is, easily traceable, I would almost assuredly guess it is.
I think you should suggest that your friend purchase the software, even if for a trial period to test it out. I can attest that I recently purchased a copy and the only regret I have (at this point, while Iโm installing it) is that I didnโt purchase a copy for longer than a year; itโs truly a wonderful piece of software.
Best wishes,
Kimmy