Normal
When you board the ship for the first time you will insert your card into a machine at security. That machine will take your picture and imbed it on the magnetic strip on the card. When you exit the ship you will insert the card in to the machine. It will show your picture on a screen so the security guard sees that it is you getting off the ship. It also tells the ship's computer that you are not on board. Same thing when you get back on board. Insert the card. Security sees that you are the person who is supposed to be getting on board and the ship's computer knows that you are "present and accounted for". Each of you must have your own card.