title_body: At what point/percentage can beer properly "age"?
upvoted_answer: Aging, from my experience, involves the heavy proteins settling to the bottom of the bottle. Filtered beer typically doesn't need to be aged because all of that is already removed. You can consider this "pre aged" like a shirt may be "pre shrunk". Best not to buy with the assumption that it will get any smaller (or improve with time).
  
  Much of the time, aging allows the beer to mellow out a bit. I find darker beers benefit from this the  most, but it really depends on the type of beer. Lagers, stouts, porters, have to age longer than pilsners and ales, as a general rule. But whether the brewer has begun or simulated this process is unknown. I guess it's best to follow the instructions on the bottle, or look up the bottler and see if they have recommendations.