Supplying a chess engine costs money, for instance for the electricity used. The section Revenue determines how much users must pay the provider for using his engine.
The Booking Fee is charged whenever an engine is used. It is possible to set this value to zero.
The Minimum per Minute is the lowest price for which a user can use the engine. Other users can bid more than this amount at any time.
The Fixed Rate (Reliable Rate) is a higher rate at which bidding auctions are no longer allowed. Other users cannot take control of the Cloud Engine by bidding more. Users pay the Fixed Rate when there is a high demand for engines on the Engine Cloud server.