I've been tasked with coming up with a CRUD solution for WebEx users on a WebEx Meetings Server (the on-premise version). Looking through the dev centers (there are 10!... making it quite hard to get to the place you want), and reading some of the linked documents (some are from 2007 and thus from the pre-Cisco time even), I'm not quite sure anything relatest to the on-prem solution. Or is it all the same except that you have a different server url (instead of mycompany.webex.com you have mywebexserver.mycompany.com)?
APIs are a hosted solution and rely on communication between the meeting services and API service. I am not aware of any plans to implement on premise API capabilities.