Without a license SongKong runs in preview mode, nothing is actually changed.
Once you have installed a license you can then uncheck Preview Only mode, however it is not automatically unchecked because there is still good reason to run in preview only, and it would be dangerous if SongKong switched to actually deleting files without you realizing it was doing so.
Delete Duplicates has its own Preview Only flag on the Basic tab, this is independent of the
Preview Only flag on the Basic tab of Fix Songs so modifying the flag in Fix Songs will have no effect on Delete Duplicates and vice versa,
