Commercial use of pvbrowser, pvb®
The executables (pvbrowser, pvdevelop) are licensed under GPL v2 or later. 
You must publish changes to these applications under GPL again.
See https://www.qt.io/licensing/.
The libraries are licensed under LGPL v3. 
You can link to those libraries without makeing your own code open source.
Thus when you develop your own pvserver(s) it is not necessary to publish your sourcecode since your pvservers are only linked to our libraries and eventually further libraries that you want to use.