I stopped at Sheetz this morning to grab a cup of coffee, and had to flip through over a dozen little tags on my key ring before I found the right one for the clerk to scan.
I’m not really complaining about using these tags. Ten cups of coffee purchased at the gas station earns me one free cup, plus they give me 3 cents off each gallon of gas. Our local grocery store has a program that lets you earn credit toward gas purchases, plus your organization can turn in the receipts and get back 2%. (If you see somebody digging in the trash cans, it’s probably a member of our church.) Most drug stores have some sort of “preferred customer” program, and my library card is also on my key ring.
As I was searching for my Sheetz card, I asked the clerk if she was old enough to remember Baltimore’s Charge-a-Plates. It was a metal plate, maybe 2 inches by one, with your name and address embossed on the front. The edges turned over to seal a piece of paper with your signature. Each of the big department stores in Baltimore had a notch on the card. The salesgirl – always a woman – put the card into a machine very similar to the ones in use today, where you slide a bar back and forth over the card to imprint the customer’s name and number. AND, you only had to carry ONE card!
Baltimore also had a delivery business, so you could buy an item at, say, Hutzler’s, tell the clerk it was C.O.D., and the next day, a big brown truck would pull up in front of your house, you’d pay the man, and voila! Plus, it was free.
Those were the days, my friend, those were the days!
thisendoftheswamp 
When I was in college our Alumni foundation used a system like you describe. Each graduate had a metal plate with name, address, and notches for the departments and the amount of donations they’d made to the college. They did mailings by running the plates. It was burdensome. Now, a computer will run labels in minutes.
Yes, those were the days of telephone cords and metal cards.