Such informations are not public: Liberkey is free but not open source
Most of the applications from the catalog are 100% portable, it means all files remains in the application folder.
For the others which are not 100% portable, they have been "portabilized" using LiberkeyPortabilizer, consequently after closing liberkey, those files/registry entries/traces are removed from the host computer (well except it there is bugs in portabilization, nobody is perfect)