It's a historical artifact in this case. There was no commercial offering. But then I got requests for particular features and ongoing maintenance / support. This then became the additional parts you can buy.
I tried to look, but you want me to evaluate your project by going through the manual and search for the "Pro" tag (as per your documentation [*]) while here you tell us "look at the home page".
Your project is great and your work is much appreciated,thank you for that. What I am seeking is clarity of the offering, because if I choose FBS for my floss project, I do not plan to pay 50€ for a hidden cost.
[*]
> Support for the latest versions of Python, PyQt6, PySide6 and PyInstaller.
> All features marked Pro in the Manual.