Does AdMob work on Windows Phone 8.1 ?

Short answer yes. If you are a developer outside the US and you want to write software for Windows Phone 8.1 you'll probably be interested in adding some ads to your application. One of the best mobile ad provider is AdMob from Google. Good news is that AdMob is available on both Windows Phone 8 and 8.1 Silverlight but NOT in the universal applications. Also note that in Windows Phone 8.1 Silverlight the ads will work if you run your application in the emulator but will not work on your own development phone. This is normal, no need to panic, just test it on another phone and you will see it works.