User api key
Perhaps my wording was incorrect. I was trying to give users the ability to create their own app. I assumed they would need to generate keys for their app.
For example, if I want someone in one of my quotas to be able to update a song title via the api. Only users of a specific quota can update song title.
Their application would need a key to connect to the api. They they would log in via their application, and if their credentials were with a quota that allowed them to update the song title, the could make a put request.
But first they need an application key. And it seems at the moment, I have to create the keys for each user that wants to connect their application to the api. There is no way for them to create their own app key.