Their website states
You don’t need to be a Costco member to purchase Costco Pharmacy prescriptions online or at our warehouses. Our Pharmacy counter will accept several different forms of payment, including cash, debit/ATM cards, Costco Shop Cards, and Visa®.
You can just go in, everywhere.
Also you can get a gift card of any value and keep it forever to get in.
Yes, this is end of night club drug hallucinating