Kanban, Gantt charts, milestones, idea collections, file uploading, retrospectives, time tracking, documentation, etc… all supported with the selfhosted version.
These are the “premium” features:
Custom fields
Pomodoro timer
Whiteboard
Program plans (I really don’t understand what is different about this than goals + milestones + documentation + tasks)
Strategies (pretty much just collecting and categorizing goals it seems)
I hope they don’t remove features and make people pay for them. It has plenty of features to make it useful now, but if they start removing them, then I think i will have to find another solution.