5 Years or so, but storage conditions and oil type have an impact. keep it in a cool place in a sealed container and you'll be good to go.
see: Oil Bible
Buy the 5 gallon bag-box with the spout on it and use it to refill an old 5 Liter oil bottle. This will keep the oil in the bag-box from being exposed to the air, and is a convenient way to get it to the car/truck. As long as you limit the amount of air(Oxygen), moisture, or extreme temperatures the oil is exposed to it will probably out last the five year mark by quite a bit.
Unless you are using this for a lawn mower or motor cycle or some other small engine, you will probably use 4 qt's minimum for an oil change. Which is 1 gallon, that's five oil changes, or 2.5 years for one vehicle if you change the oil every 6 months.