Our intended use case for the custom license fields is to use them as flags for the 20+ services that our software offers which are included/excluded depending on whatever license the user is running. It would be great if there was a way to look at the full list of custom license fields associated with a license without needing to know any of their keys, however it seems like the only way to access the fields is TA_GetFeatureValue which requires a reference to a specific field.
Is there any way to grab all the fields instead?
From your app? No.
From the web API, which could then be compiled into your app? Yes.
Or, since it's such a low number it would be quicker to just copy&paste the license fields you'll be reading from the app.