I have raised a forum post on this before and was given some advice on implementing this myself. I haven't had time to try yet however.

These features really need to be integrated into the engine for android and IOS for people to seriously consider creating apps with the engine. It's just the way the marketplace is. Without these features I don't think esenthel can compete with other engines for mobile because most have this integrated.

I disagree, they don't need to be integrated. In-App billing system and Ads is not what will make EE be competitive to other mobile engines. If In-App billing system and Ads had been so important there would be a major hurdle, funny enough(to me) mostly I only see people saying 'it is nice to have' rather than a 'must have' or 'really need' it.

Edit:
Here you go.
Android
Advertisements
Payment

IOs
Advertisements
Payment

In my opinion, In-App billing system and Ads could be integrated, but these features usually are implemented in diferent form in each game. And SDK's change very fast, would be an additional effort for Esenthel. Right now, I'm with Zervox, there are other things to improve in first place.

PD. I will need to integrate In-App purchases with EE too.