It's not free. When you complete the offers the owner gets money from you doing the offer. When you reach the correct amount of money he buys you the domain. So he's buying it for you. It's not free.

Umm it's free to me and many other people because they don't care about the fact that the owner gives you credit for completing offers. There not paying for it. So it's FREE. You don't need to complete offers either. Just referr your friends and have them complete offers. So basically you don't do all the work. And he doesn't buy it for you, He gives you credit to buy it your own domain.