Control of a printer involves reading a cartridge identification number from a memory in a cartridge and storing such number, generating status information including such number and may further include a calculated ink usage amount, and sending the status information to a data processing apparatus, which may be a server. In some embodiments, the ink usage amount is calculated as a number of discharged ink shots. The server saves the status information. This or another upstream server can reliably determine the number of ink shots used by the printer only for printing from this status information. Such control is embodied in a program stored on a non-transitory controller-readable medium, which program is executed by a controller in the printer.