A functional device includes a local wireless transceiver for communicating with a remote wireless transceiver through a protocol according to which the local transceiver maintains a record of its connection state with selected devices that are within range of it. The device includes a memory for storing the identity of a selected device; and a controller configured to inhibit one or more functions of the functional device if the connection state maintained by the transceiver is indicative of the selected device being out of range. The performance of the functions of the device is independent of the local wireless transceiver.