I think I hold the world record for the most booze brought into a house in a day without throwing a party.
My friend who works at a recycling plant gets all sorts of expired yet perfectly fine brews. Today he said to drop on by his place for some free beer he acquired. Little did I know he would give me 24 mini kegs of Heineken. Thats about 31 gallons of this beer. Their less than a month over expiration so their still good.
Just so you know, beer that is sealed and was bottled correctly won't ever 'go bad'. At least it won't become rancid or spoiled. The flavor profile will change over time, and a lower alcohol beer such as Heineken will change faster. At worst it will end up tasting like bitter water.
You will also need to keep it cool, or at least not hot. If you are storing beer you should not let it get warmer than 90 degrees or so. Other people might say 75, anyways, less is better.
I am not sure how mini kegs seal. If they seal like a pop can, you're good for ever. If they have a rubber or other kind of seal, you only have as long as the seal is good. Basically its the same as canned food.
This is completely hearsay
but I have heard of people having 20 year old Bud out of a can and not being able to tell the difference from fresh.