I am currently developing a software using Qt4.6 and QCustomPlot. The software is intended to be downloadable with the following conditions:

- free of charge for academic users and public users (altough the latter will probably not have any particular reason for using this software)

Then there's the tricky part:
Our research group collaborates with a commercial company that is interested in using the software for their services.
Are they allowed to use the software and turn a profit from its results?
Are we allowed to sell the software for commercial use?

If we link to Qt libraries dynamically, how do we go about linking to QCustomPlot dynamically?
Do we need a commercial license for our software if we link everything dll and provide source codes from our download site?

I'm thankful for any answer.