How long does a yeast colony live for?

It really depends on the strain of yeast and the environment the yeast is in. For purposes of beer brewing, yeast produce alcohol as waste during anaerobic cellular respiration, and they can survive in an environment of up to roughly 10-14% alcohol before dying out. Of course, different strains of yeast have different alcohol tolerances and most modern brewing yeasts have been bred to expedite alcohol production, effectively shortening their lifespan but increasing the rate of beer production.