As you know I'm new but I've been watching of\ver the features of AA . I have a few suggestions to make to you.
Premium users get to have features in Apps other don't. It would be col you could incorporate Forum Points for Premium Forums and / or free Giveaways on Forums and Codes or Discounts .
using IP.Nexus Forum Software bundled with Invision Power Board you can create an Appstore which people can purchase from . It uses lots of features such as bank and Redeeming Codes which could be given to premium Users for free.
This helps people encourage them buy AA Premium
A good thing would be creating a nice Premium Page with all the features listed in detail . This could be done in the forums themselves using IP.Content Plugin!
Would love to here Staff's and People's opinion on this matter.