[Zubersoft]

I wanted to avoid using in app-purchases, so that's why there are two separate applications. To transfer your library, create a library backup in the free version under Settings->Backup and Restore->Backup Library and you can restore that file in MobileSheetsPro. It will replace your entire library, so if you've already started adding songs, you can't use that approach. You would have to instead long press to select a song, tap the select all button in the floating toolbar at the bottom right, then tap Share->Export as .msf. You can then use Import->Local File in MobileSheetsPro to import that .msf file which will create all of those songs.

Mike