Well, Aeria can check any account's IP and activity. Recently i heard that they can even check in-game chat log o.O
I think Aeria know which accounts relate to each other. That's why i am asking
There is absolutely nothing wrong with having multiple accounts. So long as you do not SHARE accounts. That is when your actions become bannable. I have at least one character in every faction. I play them when I want to hang out with other friends, meet new people, or just change it up a little.
So just don't give anyone any of your accounts and don't use other peoples and you are in the clear.
And yes, you can buy ap for any of your accounts, it's your money, not like they are gonna say no. xD