Well, it's not impossible.
Simple ads can be done. You can include ad scripts on the page that the game is embedded on (outside of the game)...or, if you want an ad in the game itself, you can include a banner sprite, with an on touched object (or on object clicked)> browser>open url in new window event.
But, as I said, it's only for simple ads. If you want something more complex, I'm afraid Froweey is probably correct.