Please help!

Feline Urinary

Hello everyone, so my cat gets crystals in his bladder and has been eating Pro Plan Urinary ST/OX prescribed by my vet for the past 7 months with no issues…i was going to get him a new bag today because he’s almost out and completely forgot about holiday hours…was going to order offline but they need proof of prescription which i don’t have. Any suggestions on what to feed him over the weekend? Pet smart has Hills urinary care and Royal Canin Urinary SO, but i’d rather ask yall first to get any professional opinions. It would only be tomorrow night until monday morning. I’m sure he’ll be fine off his food for a day and a half i just get nervous. TIA!