How long can you age an ipa? I understand IPAs are less amenable to aging than, say, a barely wine.  But how long, specifically, can you age an IPA - days, months, a year or two?
DIPAs generally have a high enough ABV (7%+) to age for a few months...but you probably don't want to.

Most contemporary IPAs and DIPAs are best drank within 3 weeks from the date of bottling.  Stone's "Enjoy By" Series gives you 5 weeks to drink the IPA if properly refrigerated.  Super hop-bursted IPAs with a ton of aroma like Heady Topper recommend to drink them within 2 days, claiming the flavor and aroma begins to degrade after only a few hours if unrefrigerated.

One notable exception is Dogfish Head's 120 Minute IPA which is super high ABV and can probably be considered a barleywine for the purpose of aging.

Less intense IPAs like Long Trail's Vermont IPA could probably keep up to 2 months, maybe 3 with really good refrigeration but not much beyond that without starting to taste real strange and losing a lot of their floral and herbal notes.