Abstract: A system for purchasing service, as parking of a vehicle in a space requiring a fee, comprises storage devices operable of storing a paid service fee and controlled by the purchaser of the service and an information feed device, which is not controlled by the purchaser. The storage device can be connected, when required, to the information feed device to be fed information equal to the magnitude of a purchase. The storage device and the information feed device are provided with interconnected electrical decoding means which interchange coded electrical signals to test electrical characteristics of a storage meter to determine that it is one belonging to the system before information is fed to it.