A few years ago friend gave me a 3.3lb can of hopped extract that was around 15-16 years old.
Just for grins and to keep it cheap, I used (new) dry yeast and supplemented the extract with 1lb. Extra light DME and 2lb. white sugar to make up a 5 gallon batch. I finished it with some left over hops (1/2 oz. Horizon at 5 min and 1/2 oz. Horizon at 0 min). The result was actually quite good. The extract had turned almost black and had a bit of licorice twang to it, but the beer was clear and would easily stand up to any current brown ale recipe.