Originally Posted by KuntzBrewing
The same amount of time it would be good in bottles the beer is still the same.
This. And there's no rush to drink the beer once you start, in case that was part of the question. When you use CO2 to push the beer, the keg is a closed environment. This is unlike buying a keg of commercial beer and using a hand pump where you are introducing outside air/oxygen in order to move the beer. That oxygen will eventually cause the beer to spoil, which is why you have to finish the keg quickly. With CO2 you can drink a lot or a little and the rest will still be fine next week or next month.