Personally, I tell my beta-testers they can use my products in renders or comment on images in the gallery if they want to but I leave it entirely up to them as to whether they do or not. I do occasionally give away copies to other people just because I like them but I put no strings on those - they are gifts pure and simple.

"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." -- Bruce Graham