Make sure to install the latest Novation USB Driver from the Launchkey MK4 Downloads page:

downloads.novationmusic.com/novation

Once the driver has been installed successfully, with Ableton Live open and the Launchkey MK4 connected, go to:

Options > Settings > Link, Tempo & MIDI

Under the Control Surface section, select 'Launchkey MK4':

Under the Input and Output sections, select the DAW ports - these will appear either as '(Port 2)' both for Input and Output, or 'MIDIIN2 (LKMK4 MIDI)' for Input and 'MIDIOUT2 (LKMK4 MIDI)' for Output:

Under the Track and Remote sections, the settings should match the following:

Enabling MPE for the Input Ports section means that all MIDI channels are in use, so it's not possible to set a track to discretely respond to one MIDI channel. For this reason, it is disabled in the above settings, but you may wish to enable it if using Polyphonic Aftertouch data from the pads.

If set up correctly, the DAW, Plugin, Mixer, Sends, and Transport pads light up when holding down the Shift button. The Live Control Surface selection should also appear in the Session view (below shown in red):

Make sure to install the latest Novation USB Driver from the Launchkey MK4 Downloads page:

downloads.novationmusic.com/novation

Once the driver has been installed successfully, with Ableton Live open and the Launchkey MK4 connected, go to:

Options > Preferences > Link Tempo MIDI

Under the Control Surface section, select 'Launchkey MK4':

Under the Input and Output sections, select the DAW ports - these will appear either as '(Port 2)' both for Input and Output, or 'MIDIIN2 (LKMK4 MIDI)' for Input and 'MIDIOUT2 (LKMK4 MIDI)' for Output:

Under the Track and Remote sections, the settings should match the following:

Enabling MPE for the Input Ports section means that all MIDI channels are in use, so it's not possible to set a track to discretely respond to one MIDI channel. For this reason, it is disabled in the above settings, but you may wish to enable it if using Polyphonic Aftertouch data from the pads.

If set up correctly, the DAW, Plugin, Mixer, Sends, and Transport pads light up when holding down the Shift button. The Live Control Surface selection should also appear in the Session view (below shown in yellow):

Launchkey MK4 will not function to its full potential in Live 10 or earlier, however, you can still use it as a generic MIDI controller, as per the steps below. Alternatively, you can install the included copy of Ableton Live 12 Lite for free for more advanced control: How to install and activate Ableton Live Lite

With Ableton Live open, go to the 'Link MIDI' tab in the Live Preferences:

Options > Preferences > Link MIDI

Then, match the MIDI settings below (here shown for a Launchkey MK4 61):

You can then use generic MIDI mappings in Live to map the controls of your Launchkey MK4 (e.g. encoders, faders, Transport buttons, etc) to the Live controls. See this Ableton Support article for reference: Making custom MIDI Mappings

Features that are not possible without the Ableton Live integration mainly include, but are not limited to; Clip Launching, Plugin control, and Capture MIDI.

A video showing how to set up Launchkey MK4 in Ableton Live on a Mac can be found here: 

With Ableton Live open and the Launchkey MK4 connected, go to:

Live > Settings > Link, Tempo & MIDI

Under the Control Surface section, select 'Launchkey MK4':

Under the Input and Output sections, select the DAW ports 'Launchkey MK4 (DAW In)' and 'Launchkey MK4 (DAW Out)' (below shown for a Launchkey 49):

Under the Track and Remote sections, the settings should match the following:

Enabling MPE for the Input Ports section means that all MIDI channels are in use, so it's not possible to set a track to discretely respond to one MIDI channel. For this reason, it is disabled in the above settings, but you may wish to enable it if using Polyphonic Aftertouch data from the pads.

If set up correctly, the DAW, Plugin, Mixer, Sends, and Transport pads light up when holding down the Shift button. The Live Control Surface selection should also appear in the Session view (below shown in red):

With Ableton Live open and the Launchkey MK4 connected, go to:

Live > Settings (Preferences) > Link Tempo MIDI

Under the Control Surface section, select 'Launchkey MK4':

Under the Input and Output sections, select the DAW ports 'Launchkey MK4 (DAW In)' and 'Launchkey MK4 (DAW Out)' (below shown for a Launchkey MK4 49):

Under the Track and Remote sections, the settings should match the following:

Enabling MPE for the Input Ports section means that all MIDI channels are in use, so it's not possible to set a track to discretely respond to one MIDI channel. For this reason, it is disabled in the above settings, but you may wish to enable it if using Polyphonic Aftertouch data from the pads.

If set up correctly, the DAW, Plugin, Mixer, Sends, and Transport pads light up when holding down the Shift button. The Live Control Surface selection should also appear in the Session view (below shown in yellow):