The code is on the host's screen, in Stab on a Mac, an iPad or a PC. Or scan their QR code.
Keep songs in Stab Cloud: open them here, and in Stab on your Mac, iPad or PC, with their history. An account is free.
Open a song in the full editor, or a Guitar Pro or MIDI file of yours: play it, change it, rearrange it. Nothing is kept once you leave.