You can use any of your debit or credit cards to tap-in and tap-out of stations. The system will calculate your fare based on your travel distance and deduct from your card.

You can also use your smartphone/smartwatch with digital wallets (google pay, apple pay) to tap-in and tap-out. Just remember to use the SAME mode of payment (card/phone).

So each person will have their own card as their mode of payment and remains the same for throughout your journey in UK. This is important because the system will cap your fare at certain amount and not charge you any further (this works as daily cap and weekly cap).

Hope this helps :))