Tim Boyle/Getty Images Costco members are usually asked to show their membership cards at the door. Business Insider spoke to seven Costco employees about what happens when a Costco member can't — or won't — show them their card. They said that if you ever forget your membership card on a Costco run, bring your ID to the membership desk in order to snag a replacement. It's an aggravating scenario for any Costco member — arriving at the warehouse only to find that you've forgotten your membership card. Because Costco is a members-only warehouse club, members are expected to show their cards upfront.