Costco, $COST, has said it is cracking down on members' families using ID cards,

Costco, $COST, has said it is cracking down on members' families using ID cards, saying that shoppers who purchase their items through the self-checkout lane will be asked to show their member ID & photo in order to confirm that they pay the annual subscription fee.

“We don’t feel it’s right that non-members receive the same benefits and pricing as our members,” the company told Insider.

“As we already ask for the membership card at checkout, we are now asking to see their membership card with their photo at our self-service checkout registers.”

The company added: “Costco is able to keep our prices as low as possible because our membership fees help offset our operational expenses.”

Costco boasts 125 million authorized ID holders, according to the most recent SEC filings.