To use Apple Pay you need to authorise every transaction made with Apple Pay with an enrolled BT card, via Face ID, Touch ID or password.

Apple Watch devices feature "Wrist Detection", which, when enabled, forces the user to enter their password every time they put the watch on their hand.

These features prevent people other than the user from using Apple Pay on their iPhone, iPad, Apple Watch or Mac.

If a device with BT cards set up in Apple Pay is lost/stolen, you must go to the Apple ID account page or use the "Find My iPhone" feature to suspend or permanently delete the ability to make Apple Pay payments with the lost device.

On the Apple ID account page, select the device after signing in. In the information displayed, select the "Apple Pay" section and click on "Remove" or "Remove all".

The card or cards will be suspended or deleted from Apple Pay, even if the device is offline or not connected to a mobile network or Wi-Fi network. 

You can also call your card-issuing bank if your device is lost/stolen to suspend or delete cards from Apple Pay. 😊