The present disclosure relates to a method for determining a functional inventory of a functional unit, wherein in the functional unit at least one function that has already been installed can be enabled and thus activated in each case and/or at least one function can be subsequently installed and so that it can be activated in each case and wherein the functional inventory of the functional unit represents the set of functions that are actually activated. The current functional inventory of the functional unit is determined by a control device of the functional unit and an actual inventory specification is generated for the current functional inventory, which describes the determined functional inventory, and in an external server device, a target inventory specification relating to a target functional inventory is requested from a predetermined blockchain credit account and in the event that the determined actual inventory specification differs from the target inventory specification, a predetermined forcing measure for predetermining the target functional inventory is triggered.