Seems like some places require the card every time you visit, others check it once and only need your ID from that point onward (until the expiration date I assume).
I can't for the life of me find my card right now (it's somewhere at home, but we're moving so it's a shambles), but I'm 'checked in and registered' at a few places that might let me buy without it since I'm already a customer...
My renewal is in a few months so I'll have a card again at some point here, but I wish they'd have just made it a credit-card sized thing that didn't stick so far out of my wallet so I could leave it in there 24/7.