A method of operation performed by a charging system node of a charging system associated with a communication network, the method comprising: recording consumption control information in a parent data container that is common to a plurality of user devices that share a subscription for using the communication network, the consumption control information commonly governing consumption by each of the user devices of units that represent corresponding quanta of metered use of a communication service provided via the communication network; and recording individual consumption information for each user device in a correspondingly created child data container that is specific to the user device, the individual consumption information reflecting unit consumption by the user device that is subject to the consumption control information in the parent data container; wherein, for charging-system operations that involve only the consumption control information, the method includes accessing the parent data container without accessing any child data container; and wherein, for charging-system operations involving unit consumption by a particular one of the user device that is governed by the consumption control information, the method characterized in that it includes forming a non-persistent working data container, tracking the unit consumption in the working data container, along with holding the consumption control information in the working data container to govern the unit consumption, and, in conjunction with releasing the working data container, updating the individual consumption information recorded in the corresponding child data container, according to the tracked unit consumption wherein the plurality of user devices is a plurality of Internet-of-Things (IoT) devices sharing the same subscription, wherein the consumption control information comprises a periodic credit allocation, as a consumption allowance, that allows each IoT device a defined amount of usage of the communication network, wherein the credit allocation is a credited number of units, wherein the method includes refreshing the periodic credit allocation by accessing only the parent data container, and wherein governing consumption by each IoT device comprises authorizing usage of the communication network by the IoT device in dependence on verifying that the periodic credit allocation in the parent data container is valid for the current period, and further in dependence on verifying that the IoT device has remaining units from the credited number of units for the current period, as determined from the individual consumption information recorded for the IoT device in the corresponding child data container. recording consumption control information in a parent data container that is common to a plurality of user devices that share a subscription for using the communication network, the consumption control information commonly governing consumption by each of the user devices of units that represent corresponding quanta of metered use of a communication service provided via the communication network; and recording individual consumption information for each user device in a correspondingly created child data container that is specific to the user device, the individual consumption information reflecting unit consumption by the user device that is subject to the consumption control information in the parent data container; wherein, for charging-system operations that involve only the consumption control information, the method includes accessing the parent data container without accessing any child data container; and wherein, for charging-system operations involving unit consumption by a particular one of the user device that is governed by the consumption control information, the method characterized in that it includes forming a non-persistent working data container, tracking the unit consumption in the working data container, along with holding the consumption control information in the working data container to govern the unit consumption, and, in conjunction with releasing the working data container, updating the individual consumption information recorded in the corresponding child data container, according to the tracked unit consumption wherein the plurality of user devices is a plurality of Internet-of-Things (IoT) devices sharing the same subscription, wherein the consumption control information comprises a periodic credit allocation, as a consumption allowance, that allows each IoT device a defined amount of usage of the communication network, wherein the credit allocation is a credited number of units, wherein the method includes refreshing the periodic credit allocation by accessing only the parent data container, and wherein governing consumption by each IoT device comprises authorizing usage of the communication network by the IoT device in dependence on verifying that the periodic credit allocation in the parent data container is valid for the current period, and further in dependence on verifying that the IoT device has remaining units from the credited number of units for the current period, as determined from the individual consumption information recorded for the IoT device in the corresponding child data container.