I need to create an app for my campground to allow my office people to issue WiFi voucher codes to our customers. My gateway can generate a list of codes which I would upload into the Creator app. When my staff sells a voucher code, I would like to have the code they select no longer available for re-issue. Can someone point me in the right direction to how I would accomplish this?

I've been searching the community and have not been able to find anything pertinent. Conceptually I wonder whether I need some sort of inventory function that removes or marks a voucher code as sold when it is sold so it would not display when we are selling a code to a customer?