To clarify, I mean an NWC subscription to use the API from the app itself, not a per-user fee, and it doesn’t require sign-in. I could choose to add a session fee on the app side, or keep it free to the user, depending on the cost.
Discussion
Yes, this is a good idea.
You would have to use an API key in the client, which is the same as loading credits on a nostr key and using it in the client. It's basically the same