[PyQt] Help with PyQt licensing question

[Elias Bachaalany]

Hello,

I have the following situation and need some help regarding licensing of 
PyQt.

There is a main program (main.exe) that is extensible via plugins.
main.exe does not know about the nature of its plugins.

The plugins are general purpose, they can do many things to change the 
behavior of main.exe.

main.exe is closed source.

One plugin could be hosting LUA scripting language.
Another plugin can be not related to scripting.

There is yet another plugin (plgpython.dll) that hosts Python and is 
open source (with New BSD License). Since plgpython.dll hosts Python, it 
can also host PyQt.

Now my question is: do we need a commercial license of PyQt if we own 
main.exe (paid for it) and use the open source / free plgpython.dll 
program to run PyQt scripts?

Thanks,
Elias