I have noticed that there is only one option to implement ads through engine and, if I understood it, the Epic Game Ads cover only desktop-web versions of the game.
I don't want to panic but I did sign up 7 days ago (on 28th) and my account is still pending approval

But even if they accept my account it only covers desktop-web games.
I was hopping that EGA plugin features some sort of Iframe box but it shows in a script like this:
<Ads adsId="xxxxxxxxx"/>.
I'm not sure if it would be hard to implement Iframe box as a feature in the engine but it would solve a lot of problems concerning how to monetize the game.
This is my experiment with LeadBolt ads and Cyberix SWF export version of the game:
ddteam.byethost32.com/cyberix/leadbolt_test.html
I inserted a simple Iframe code in the html file...
<div style="text-align: center;">
<iframe src="http://ad.leadbolt.net/show_app_ad?section_id=907811511" width="320" height="50" align="middle"></iframe>
</div>
...and the dummy-ad is showing up under the main-game window. Since it's an android ad-service, the dummy-ad content is showing only when the link is accessed with mobile device, on desktop browsers it only displays empty Iframe window.
Next test is an APK with simple Iframe box inside a game-window (inserted through the C2 plugin) and the same code from first test inserted in the same way in the main html file. The APK file was converted from HTML with free online service called
Cocoon.
drive.google.com/file/d/0B45BeJ8IYXbEWnM...Nk0/view?usp=sharing
I don't really understand SWF files and their relation to HTML but I (want to

) believe that a simple Iframe box feature could solve monetize-problem with APK files. Unfortunately the web ad service for desktop is much harder to find since everybody is now mobile-platform oriented.