I have yet to use Gizmo, free or donated. I will say this, I like the idea of developers buying x amount of keys, and selling two products, one with, and one without. However, two issues I have with it. First, if a developer's aircraft doesn't sell as well as they expect, then they have wasted a lot of money on keys they can't use. If a system can be set up so that when an aircraft is sold for the price with key, a system buys automatically one key and provides it to the buyer. One more thing, don't make the price difference 5 dollars, make it 10. So basically, slightly change Arno's idea.