4 keys and now?

[Unregistered]

When I have one product 4 keys, is there a level more I can get when I product this product? I seems to collect keys but nothing happens, even after 30 productions. Is ist just to get coins?

[Ellie]

After achieving 4 keys for a contract, you have mastered that product. Only return you get now is the 5% increase in coins.

Move onto another one