One tobacco stick will last for one session, and you shouldn't re-use a tobacco stick. 

Once you've ended the session, your Ploom device will turn itself off (you'll know this is happening because you'll feel a long vibration and see the lights turn off). Take out your used tobacco stick carefully - it might be hot straight after you've used it. You can leave it in a stick tray until it cools down, and then put it in the bin. 

To find out more about replacing your tobacco stick, watch our video.