A system for printing an imprint on a flat materal comprising - a cartridge unit holding a usable total volume of a consumable, in particular ink, and - at least one material processing device , in particular a franking machine, which comprises a printing device (102.6) designed to use the cartridge unit and a first data processing unit (102.1) connected to the printing device (102.6) for controlling the use of the cartridge unit to produce the imprint, wherein - the material processing device is configured to detect insertion of the cartridge unit into the printing means (102.6), - the material processing device is configured to generate current consumption information representative of the use of the cartridge unit by the printing device (102.6) since insertion, - the cartridge unit has a first memory (107.1) in which a unique cartridge identification of the cartridge unit is stored non-volatilely, in particular unchangeably, - the usable total volume defines one or more of consumable volumes of the cartridge unit , wherein - the first data processing unit (102.1) is configured to cause, at least when at least one predeterminable usage-relevant event occurs, a storage of a current use-information generated by means of the current consumption information logically linked to the cartridge identification in at least one second memory (102.3, 106.6), the usage-relevant event being relevant for the use of the cartridge unit by the printing device (102.6), and - the first data processing unit (102.1) is configured to write to an irreversibly writable memory area (111.1, 111.2) of the first memory (107.1) when the usage-relevant event occurs in order to mark a consumable volume associated to the memory area (111.1, 111.2) as consumed, wherein - consumable volume associated to the memory area (111.1, 111.2) is still usable when the at least one predeterminable usage-relevant event occurs and can be freed for usage by the first data processing unit (102.1) using the current use-information. - a cartridge unit holding a usable total volume of a consumable, in particular ink, and - at least one material processing device , in particular a franking machine, which comprises a printing device (102.6) designed to use the cartridge unit and a first data processing unit (102.1) connected to the printing device (102.6) for controlling the use of the cartridge unit to produce the imprint, wherein - the material processing device is configured to detect insertion of the cartridge unit into the printing means (102.6), - the material processing device is configured to generate current consumption information representative of the use of the cartridge unit by the printing device (102.6) since insertion, - the cartridge unit has a first memory (107.1) in which a unique cartridge identification of the cartridge unit is stored non-volatilely, in particular unchangeably, - the usable total volume defines one or more of consumable volumes of the cartridge unit , wherein - the first data processing unit (102.1) is configured to cause, at least when at least one predeterminable usage-relevant event occurs, a storage of a current use-information generated by means of the current consumption information logically linked to the cartridge identification in at least one second memory (102.3, 106.6), the usage-relevant event being relevant for the use of the cartridge unit by the printing device (102.6), and - the first data processing unit (102.1) is configured to write to an irreversibly writable memory area (111.1, 111.2) of the first memory (107.1) when the usage-relevant event occurs in order to mark a consumable volume associated to the memory area (111.1, 111.2) as consumed, wherein - consumable volume associated to the memory area (111.1, 111.2) is still usable when the at least one predeterminable usage-relevant event occurs and can be freed for usage by the first data processing unit (102.1) using the current use-information. <EOS>