"Ableton app" is not optimised for your Mac and needs to be updated
- Live Versions: All
- Operating System: macOS 10.14, 10.13.4
Certain components of Ableton Live 10 are in the process of being updated for full compatibility with future versions of macOS.
Starting with macOS High Sierra 10.13.4, apps that have not been updated to use 64-bit processes produce a one-time alert when opened. This gives users advance notice that they are running 32-bit software, which will not be compatible with macOS in the future. In macOS Mojave, this alert appears once every 30 days when launching the app.
If you receive this notification when starting Live, just click "OK". It doesn't affect the functionality of Live in any way, nor does it pose any security or stability risks.
Full details on Apple's website: 32-bit app compatibility with macOS High Sierra 10.13.4 and later