Varispeed is a MaxForLive device that allows you to transpose your entire Live set in Ableton Live.
Similar to the Varispeed option in analog tape machines and DAWs like Logic pro.

It transposes all Audio/MIDI clips in both Session and Arrangement View by up to -24/+24 semitones while accurately changing the Live Set’s tempo.
It can also automatically transpose:

• The Root Note of individual Audio, and MIDI clips, and your Live Set.
• Simpler devices in Slicing mode,  and Serato Sample plugins
• AutoTune plugins - Antares, Waves, Nectar, MetaTune, Melda, Melodyne, Xpitch, and AutoTuna - (AutoShift is also compatible)
• Certain Antares effects/Instruments. (EFX, Slice, Harmony Engine, Vocodist)
• A few other built in Ableton Live and M4L devices. (Like Shifter, Corpus, and Resonators)
• You can also Transpose MIDI information after leaving clips such as sequencer and chord generator outputs or individual Drum Rack cells (see VPitch section for details).

Exclude specific tracks like drums, or DrumRacks. by adding a keyword or symbol to their names, keeping their MIDI and audio clips untouched in your Live Set (See Exclude section for Details).

This gives you the ability to explore your song in a different key, and record parts in different speed and pitch with one click.