Hi there,
Firstly, being 15 doesnt make you too young for the game. Also, depending on your attitude and level of maturity - can be hard to tell exactly how old someone is if they dont say anything!
How much you benefit from paying depends soley on yourself. Just like anything - the more you put into something, the more you get out. So, the more you want to play, have fun, explore what there is to offer and make some friends - well the better overall your experience will be.
You can get a good idea as to what is available with the expansions from our guides in the Knowledge section. The classic Ao and Notum Wars is what you get for free if you just download the small client and go on the "Free to play" scheme. The rest in there - so Shadowlands, Alien Invasion and Lost Eden are all separate big expansions - the biggest being Shadowlands.
With regards to Shadowlands you can pay a lower monthly fee if you subscribe
just to that - more details can be found on the official AO site I am sure!!
Once you upgrade, there is no going back.. but after all the time I have personally been playing I dont regret a second for paying for all the expansions
![Smile :)](./images/smilies/icon_smile.gif)