Tell us how exactly you do the "randomness" of each key. It's too easy for you to just say that it's random but each time, pick out a key that is of lesser value than 0.004BTC. Also, provide us with a list of the keys you can get.
Premium games can come up to date with the key. Steam comes from random game store. 0.004 BTC even very appropriate to try!
You didn't answer any of my questions completely.