After I wasn't able to get AdMob ads in my project, I created blank project to see if it is because of something in my app or..
So, I created new project and followed manual and examples from here:
I add AdMob object, added only 2 events: preload banner ad on start of layout, and show banner ad on ad received. Of course, I entered banner ID. Exported (cordova) imported into Intel XDK, added cordova admob plugin, compiled to apk, install on my phone and still no ads shown. Any ideas?