Um, so you bought software from a total stranger on a free forum site, and you expected it to be legit? Trying to save a few dollars cost you a lot, and now you are mad and trying to get a reward from turning him in.
I suggest you post at the site that he is using for this scam, and cut off his source of income. But I have to tell you that you do not stand a chance of getting him arrested, or getting a reward. This is a case of you getting what you paid for. It’s an internet scam, and people get scammed on the internet hundreds of times every day.
Suck it up, be more careful next time, and move on.