Office Online Server - WOPI

We are in the process of integrating one of our Java based application with Office for the web (Office Online Server) through Web Application Open Platform Interface (WOPI).

Office in the cloud

• In order to integrate Office Online into our applications it is required to join Office Cloud Storage Partner Program. We are trying to get registered through the link https://developer.microsoft.com/en-us/office/cloud-storage-partner-program but unfortunately we never got any response back and not even an acknowledgement. Its been a week since we had registered. Is there a way to find out what is the status of the request?
• "Office for the web only makes WOPI requests to trusted partner domains.". We have our application in an hosted environment where its been configured for different customers. In this scenario it might be required to register url of every customer under Microsoft like e.g. xyz.com/customerA and xyz.com/customerB. So our query is whether this will lead to any compliance issues?
• Business users require an Office 365 subscription to edit files in Office for the web. In our case we perform the WOPI Client request using system user (user with super admin rights) of our application. This should be irrelevant for Microsoft but should ensure that we do not get any compliance complaints
• What are the options available if our application is hosted on an intranet and not exposed to internet? Is Microsoft Online server on prem is the answer? does it work in the same way as Microsoft Online server on cloud while integrating with WOPI?
• Reference: https://wopi.readthedocs.io/en/latest/

Office Online Server on-premise

• If we plan to implement Office Online server on-premise then what is the license that needs to be procured to avail this server
• How does the licensing apply if we integrated on-premise Office Online server with our applications through WOPI
• Java applications have their own authentication and user base and how does this affect the licensing of usage of on-prem Office Online server
• Reference: https://social.msdn.microsoft.com/Forums/office/en-US/a2c5fa99-1609-429c-bdcf-c99ec8143137/microsoft-wopi?forum=os_office