[Lipa]

I'm afraid it is likely that nothing can/will be done except for you to neg rep him and learn from this.

I didn't read much, but it sounds like you offered a trial and he took advantage. There's people that go to grocery stores and eat all the samples, how's he different?

Spoiler:

I do admit, those people suck.

I think that's very much the truth of the situation. I wouldn't offer trials and not expect people to do that. While it's annoying, it's just what happens.

I see it as taking a loan from someone. You use your resources to help someone, they agree to pay you, and the never do.
It's very tedious.