I am wondering if there is a tutorial on the app key management. In particular, I am looking for answers to questions such as:
1. What is an "app" defined as?
2. Why is there no possibility to delete an app?
3. When should one use generate an new key? What is the advantage of using a new key instead of reusing an already existing one?
it is not possible to delete the app key by yourself but you can enable or disable the app key using APPKEY app.
The app key is used to identify an application.
There are some use cases such as SxS API (which also required app key) that you may publish several apps.
So using a unique app key on each published application is a good habit.