The technique of the present invention reads expendable consumption data regarding expendables consumed by each of printing devices 50a and 50b at regular intervals, sums up consumptions of each expendable with respect to each expendable manufacturer, and sets a convertible point corresponding to the summed-up consumption. The technique then notifies a computer 60a or 60b of each expendable manufacturer of the setting convertible point. This arrangement automatically sets a total point to each expendable manufacturer, based on the consumptions of the respective expendables consumed by the printing devices 50a and 50b.