I don't know what the developer is expecting really... I donated 1€ and taking into account that this is a free-time project with no guaranteed support I don't see why that donation isn't acceptable. Even if PayPal takes 50 cents in fees (which they don't), it still is a good value, and I don't know why I didn't get a key. If you don't want to commercialize this, fine, but at least give a key to everyone who donates you money... I find that policy really shady, and I don't feel encouraged at all to donate again. Good luck with the project though...