Don't be afraid to use your gift cards at the store.
This happens to us all. When you cash out for the first time with an app, get your gift card in your email, and print it out. There is a small bit of anxiety when you use it for the first time at the store. Don't be afraid to use it. It is as good as a plastic one. I used a Walmart printed gift card, and the checker looked at me like I had a leg growing out of my neck. The gift card would not scan on the belt scanner. It made me feel like something was wrong with the card, so I got worried, then she used the hand scanner and it worked fine.
I felt like a weight was lifted off my shoulders, maybe it was the leg being removed from my neck. A lot of the gift cards do not expire. Be sure to read the details on your gift cards, so you don't have the same anxiety I did. A lot of the gift cards have codes, so you can use them in the store or online at a merchant website, like Amazon, Ebay, Best Buy, etc. If you have any questions let me know, and as always "fear not its only money".