I don't see how the device replaces a card. Unfortunately, the link in the article took me to a vendor site that required my e-mail address. I'm not interested in buying the product, and I'm too paranoid to give it to them just for informational purposes.

How does a tablet replace a customer loyalty card? What do I as a customer present to confirm my membership in a loyalty program?

If a tablet is used to replace a cash register, where do employees put ... cash? Or checks, coupons, and all those other bits of paper and coin?