The application relates to systems, devices and methods for controlling enablement of resources based on a number of tokens in a token store. A resource is enabled when a number of tokens in the token store is greater than a minimum value. The resource is disabled when the number of tokens in the token store is not greater than the minimum value. When used in combination with an authorisation source, such as an authorisation source stored on a server or storage means, the token store provides a grace period during which the resource is enabled, even if the authorisation source is unavailable due to network or hardware failure, or disconnection of the storage means, for example.