When I try to render my golden piece of music out of ableton, it stops at 100% telling me that there's not enough memory, and I should save me Project and close live

What can I do except of buying more RAM?
I tried to render just half of the track, and then the other half. But also here I'm runing into the same problem.
Audio freezing/consolidation is almost not possible as I have lot of compressor/gating sidechaining running.
Any Ideas?
And one last question: Whats the difference between rendering the master track, and resampling on an audiotrack when playing my song?
tänx & cheers,