So if I want to buy Poser 4 its like $249 now.
But if I have stolen a copy then I can get it for $129.
So If I just say I stole a copy (but I really didn?t) would I get the same discount or would I have to prove I had stolen it?

This seems awfully weird. Why not give everyone a chance to buy it at the discount and not just thieves.

I would think that people with stolen copies wouldn?t give two cents for a registered copy. True there is that upgrade path but if they stole Poser 4 they will steal Poser 5.