What do you mean? The question is a bit vague.
You can't use the API outside of Revit except with Forge. If you are using it within Revit then you are publishing to the app store yes/no, so then haven't you read the terms and condition for that?
If you are not publishing to the app store, then that may be a different situation (due to lack of app review and not agreeing to terms of app store etc.) . I don't think these things have much to do with copyright however since in the end on the desktop a licensed version of Revit is required and with Forge the developer pays for processing hours.
