@SjorsScheres@RubinsteinJohn@AlexisRohou@cjrlab@structurabio You can't change it retroactively, but you can change it for future versions. You can also release it under different licenses in parallel, e. g. grant some company the right to make a closed-source derivative. All of this requires clean separation of parts you haven't authored.
@SjorsScheres@RubinsteinJohn@AlexisRohou@cjrlab@structurabio I imagine most GUIs in #cryoEM software could be made non-GPL without stepping on anyone's toes. As the field matures, ease of use becomes an equally important feature as the computational back end. Maybe something to consider when thinking about competitive advantages.