The beer inside it can keep for a year or more if stored properly depending on alcohol content, hop content, oxygen content, temperature, etc. Generally, homebrew is best within six months, but bigger beers can last far longer.
exactly. our home kegs are all CO2 driven, just like kegs in a bar.
they aren't hand pumps like the kegs at the frat house, where you're just pumping air into the keg, and thus oxidizing the beer with every pump.
and that's why it gets stale if you don't drink it quickly.
I purge as much regular air as I can, and then store em in my basement. I have 10 gallons hanging out, and 2 half full kegs on tap at all times.
kegging will make you drink more beer, and thus brew more.