I think all of the comments are good points regarding NoMachine's going closed source but
I believe that precedence is that if you have historically provided the code under GPL you have
already given those that use that software the perpetual right to continue using... just don't expect
the originator (re NoMachine in this case) to fix bugs, improve on it etc.
NoMachine also has their own issues to deal with as some of their software I have got to assume
was implemented using GPL'd code or snippets thereof so they would have had to rewrite their
own using someone with no knowledge of or access to the original code.
That is probably just one reason why the new version took so long as its nearly 18 months overdue.
Someone in the thread did mention that if NoMachine continued with some of the 3.x NX code that
was GPL'd they would have to contribute back to the 3.x source any changes they make.
But... all of the above may be nothing or just fodder for lawyers to make money arguing over.
I think it would be worthwhile to post the question on the NoMachine forum as a question and
get their official answer as it is a legitimate question that they must have decided on when they
went closed-source for the 4.x release of NX.
I'm probably the right person technically to ask the question or name what modules etc but
perhaps someone on the list could and let us know their answer.
Just a thought.
Brian