then please submit a ticket here.
Also attach your purchase invoice you got from scirra to verify your purchase. You also can find the documentation here.
2. In event sheet there is info:"If you want to use the ads function you need to add also the plugin "Android / iOS Native AdMob" at to your project."
Really? Another plugin ? Please tell me how to find it?
You need install this plugin in cocoon, NOT IN CONSTRUCT. You find it at cocoon -> [YOUR PROJECT] -> Plugins -> Cocoon.
3. You get this issue because the mentioned plugin is missing. See the documentation link posted above.
Please for all further questions, submit a ticket or use the forum.