1. A program vending system for dispensing a program which may be used in a separate programmable machine that executes the program, which comprises: memory means for storing a plurality of programs which are each suitable for use in the separate programmable machine; transfer means coupled to the memory means for transferring a selected program to a memory device contained in a program cartridge which is removable from the program vending system; a use interval circuit contained in the removable program cartridge and coupled to its memory device; and use programming means coupled to the transfer means for generating a signal to the use interval circuit in the removable program cartridge which establishes a preset use interval for the transferred program; wherein the transferred program stored in the removable program cartridge may be executed in the separate programmable machine until the preset use interval expires and the use interval circuit prevents further execution.