Postage metering apparatus is provided with a removably mounted print head module such as an inkjet cartridge with an integral ink supply. The module includes means responsive to the number of printing operations performed by the print head and to terminate operation of the print head when a predetermined number of operations have been performed. Upon termination of operation of the print head, a signal is sent to a microprocessor of the postage meter which then transmits information relating to use of the print head, and if desired postal register information, to a remote data center. The remote data center may then send an authorization signal permitting further operation of the print head.