If you hold membership minutes or banked points at a venue, you can put them toward a booking right on the booking sheet — a six-digit code proves it's you, and after that this device remembers you. (Gift cards are simpler still: see Gift cards.)
Your balance is tied to your guest record, and anyone could type your phone number. So the first time on a device, roomZy e-mails a code to the address already on your record and you type it in. After that, the booking page recognises you for 90 days on that device — no code, no link.
Fully covered → it confirms with nothing to pay, no checkout. Partly covered → the ticket says exactly what's left ("$15 to pay · was $55") and checkout takes just that. The e-mail sign-in link under Manage your bookings still works and signs you in the same way.
Staff can apply your balance for you: when they book you from the dashboard and link your record, they tick Use their balance for this booking. Nothing for you to sign in to.
Membership minutes and points cover bay time — not extras. Gift value covers anything. Whatever is left is what you pay: online, the checkout shows the remainder; at the desk, it shows as owed on the booking.
When you're already playing, the bay knows who you are from your session — so if the Concierge offers you more time and you have a balance, it's used automatically, no sign-in needed.
Memberships and gift cards are sold by the venue (online where offered, or at the desk). Points build up on their own as you play. Ask your venue what they offer.