Most of them are shared license, its not suppose to be shared to the public but most likely these people that post them up don't care as long as they get some return anyway. If in any situation the license are not renewed or cut off buyer will get cut off as well. Its like those family plan.

Kind of a grey area so taking those up comes with certain risk especially if your work depends on the software staying alive. If its for personal use its kinda like paying officials for the right to play test instead of out right pirating it.

Some are keys that they get spare, but judging from the price I'd presume its more like a family or coperate plan.