It feels a bit burdensome when someone gives you a card to go eat something delicious

Even when the person paying tells me, "Come in person and order whatever you want without worrying about the price," I still hesitate a little.
If it's not even family and they just hand me a card and tell me to go eat on my own, it feels quite burdensome.
Since it's their money and not mine, I can't easily bring myself to order expensive food.
So, I usually just eat something moderately priced.
This is because I once became a university teaching assistant only because a professor bought me expensive meals and told me to work as an assistant.