Aging Beers....question

[TheEngineer]

I popped open a bottle of a beer that I can't remember the name of right now (but can loook tonight). It was one of those that on the outside of the box (yes this beer came in a box), that suggested that aging it further would be a good thing to do.

Now I've had this beer for about thre years now in the fridge (upright), and yes I thought it was a lovely bottle. complex and smooth, but I have not baseline for understanding aged beers.

What this beer tougher, more alcoholic, etc a few year ago? Is three years a long time for a beer structured for aging? Did I open it too early / too late, etc,... Would love some insight.