SongKong uses a number of configuration files, and creates various caches, logs and reports, these can be categorised as follows:
For Windows they are all stored within C:\Users\username\AppData\Roaming\SongKong, and for Linux they are stored within $HOME/.songkong.
For MacOS the configuration files are stored in ~Library:Preferences:SongKong, the other files are stored in ~Library:Application Support:SongKong