From what I understand commercial brews don't age after bottling like a homebrew would.
This is because most beer you find in the store has had as much of the yeast as possible filtered out before bottling. In other words the beer is as good as it's going to get once it's bottled and just goes downhill from there.
In homebrew and bottle conditioned beer (you can tell because there's a layer of yeast on the bottom of the bottle) the beer will actually age well and condition due to those yeast cells constantly working on the liquid.
I'm sure there's a break off point for bottle conditioning as well but I have not heard what that might be and it would depend drastically on yeast health, storage, and gravity.
Check out this video at around 4:05
These two are allowed to sample a 139 year old "Royal Beer". In other words it was brewed specifically for the Royalty and must have been amazing at one point, however their reactions tell a different story.