That was definitely a scam then, you might've even paid for the free version. It happens. How long ago did you buy & can you remember where from? If you bought fairly recently you may still be able to get your money back. Some info here
http://www.gnutellaforums.com/showthread.php?t=28751

You can download the free version from the link in my last post. If you're happy & have no probs with it, you can always go for Pro later