key card

US /ˈkiː kɑːrd/
UK /ˈkiː kɑːrd/
"key card" picture
1.

a plastic card with a magnetic strip or embedded microchip that is used to open a door or operate a device, especially in hotels or secure buildings

:
I used my key card to access my hotel room.
Please remember to return your key card at check-out.