No, Once you bought you will get lifetime update free.
 

If you have regular license then Yes, If you have extended license then you can publish unlimited apps.
 

We have 1 licenses, With an Extended license you can create & publish unlimited apps.

Yes we do, if you have license code for xui, also we can do all types of bug fixes.
 

No, we do apps development only we dont have any source for streaming.