A method for selectively powering a battery-operated drug-delivery device, the device having a battery and a battery circuit, the method comprising: providing a battery isolator in a first position whereat it interrupts a battery circuit, whereby no power is provided to the device； and activating a fastening mechanism configured for fastening the device to a user, the activating causing the battery circuit to be uninterrupted by the isolator, such that power is provided to the device. Additionally, there is provided a selectively powered battery-operated drug-delivery device, comprising: a selectively-removable isolator disposed in a first position whereat it interrupts a battery circuit； the isolator movable to a second position whereat the battery circuit is uninterrupted by the isolator； and a mechanism for fastening the device to a user, activation of the fastening mechanism moving the isolator from the first position to the second position.
