Legally, I doubt he can do this if the ability exists, by this I mean if all one has to do is drop files into the folder structure and call an API he uses to make other modules operate.
Even covers the US, I believe there's a spat between a couple of software devs called Oracle and Google, where the API has been at issue and was found to be not covered by copyright.
Probably a restriction of trade too, esp if you were already selling addons that worked with hb.
He can, he already remove files from Github and now the documentation regarding modules, requires client login.
What makes you think he will not remove hook, api, etc, in the future? Screwing of course my install and others with them that require this features. I do, in particular for Virtualmin and other things, I require hooks, the API, etc.
This was the main reason I purchased this software, not the fancy order pages, it was the wide and open developing documentation and features, and now it seems he want this gone as well.
If I wanted a boxed limited product I would have stayed with what I was using before, and hell, even that was almost all open code, only some parts where encoded. I went to Hostbill because the power it had, after reading the dev.hostbill.com
If it was not for that page, I would probably never had purchased his software and now it seems he thinks removing or limiting this features is a good idea.
Of course his idea of doing this is just STUPID, because Hostbill uses MYSQL, this means that every single things you do in Hostbill is in the database. You can read or modify absolutely everything and he cannot possibly stop that. Anything you install in your server, could read or modify your data. He can try to restrict his by forcing other people not wanting to sell for hostbill or breaching their contracts for people that purchased after May 26, but he can“t really prevent anyone from developing his own module and reading that already belongs to you.
Hostbill is just an interface, you are still the owner of your server, and your data, and he cannot restrict how you access or manage this data. He just just making his software more limited and of less value with this and making people angry, and possible other companies will not ever develop a single thing for this software, again making the software null vs competition which can have this options.
The more I see his decision the more I convinced he is under candy. He must be taking some type of candy based in his bad decisions and his constant urgency for new money. Im hope im wrong, but there is no other logical explanations for some of his decisions.