So far I've only used it at GracieGrace. (I believe you can only use it in the city)
When you're about to buy one of her items (say...an expensive shirt around 5,000 bells) when you select "I'll take it!" and you have the shopping card with you, Labelle asks how you'd like to pay. You can choose "cash" or "shopping card". The shopping card links directly to your ABD account, in your deposit funds.
I agree!! LOL I was like "YAAAY!! WHAT'S THIS?? 83" and then when I found out how it worked I was like.. "Wow...why not just pay by cash??" T_T xD But I guess I'll only really use it if I ever become crazy enough (or get the cash) to buy Gracie's crazy-expensive furniture...Redd is NOTHING compared to her prices now.... :gyroidconfused: