Well, I'll tell you all how do they all do it and why you shouldn't be a part of it.
The companies offer agents for selling their software or making people do those offers. Then, some of these agents go this road and do this. They say they will offer free things for completing them, which makes the number of people completing the offer like 10 times. Then, the company pays them their share, and they get these things for you from that money itself, keeping most of it. They don't just empty up their pockets for you! Imagine, the company is actually getting drained out on its resources unknowingly, when its thinking that the offers will give them some return but with 99% people only doing them to get these free stuff and never look at the company again. What if this would happen to you?