To use a card at checkout, a cashier can either scan the card's bar code from the smartphone or type in the member's ID number.

WSJ: Store Loyalty Cards on Your Smartphone

Those without printers can grab a free PayNearMe card at one of 7-Eleven's 6, 000 locations and use the card's bar code in lieu of a printed sheet.

FORBES: Entrepreneurs

In a digital twist, tourists receive a card with a code number on it, and later, they can view the images online and decide if any of the prints are worth purchasing.

BBC: Expert portraits in touristy spots