The STS Association, as the custodian of the STS prepayment metering technology standard was founded in 1997. The key operational objectives of the association are to maintain the necessary infrastructure; promote the technology internationally and further develop the standard to meet emerging international demands for additional functionality. The Association ensures interoperability between system components from different manufactures of prepayment meter and vending systems by accrediting and maintaining a list of test laboratories that ensure compliance to STS standards. The Association manages the availability of encrypted vending keys to manufacturing members via its key management centres, and ensures consistent use of manufacturer identity codes as well as meter serial numbers.