The enrolled card is a digital version of your physical card, so it is valid until it expires.

When the physical card has expired, you will not be able to use it in BT Pay. 

If your card has expired, your newly issued BT card will be displayed in your card list even if you have not yet physically received it. 

Press the "Add card"button ( located in the top-right corner of the screen when you open the app), and after adding your new card details, a confirmation SMS will automatically be sent to your phone number. 

Enter the code sent in the app and you have your new card in BT Pay. 😃