Once a homebrew kit has been brewed how long will it last for once bottled or barreled?!
If you have good sanitation procedures (everything was cleaned and then sanitized before contacting the beer), if you minimized oxidation possibilities, if the beer is stored in a dark, cool place then it should last for 6 months or more.
If you washed the bottles with an old rag, left the airlock off the fermenter, used clear bottles, and stored them in your attic, they're probably already bad.
Homebrewer and beer nerd.
That depends on the beer. A strong, dark beer like a barley wine will actually improve over the years.