there is a option when rendering my finished track in ableton live to convert to mono, but why?

sometime it's useful to work with mono tracks in Ableton because they're less heavy than stereo tracks, so the pc makes less efforts with its ram.

thanks bro but doesn't that effect sound quality?

yea i only work with mono files for my radio show because it makes them twice as small. also , pro tools only uses mono files, but mixes down to stereo .

I use ableton to make samples -

load audio source/plugin instrument
cut
apply effects
render (in mono almost always)

You gotta remember.. it's a digital audio workstation.. not just tune-producing software.. needs to function in all kinds of ways.