Xamarin FAQ, 2015-11 - “Xamarin Starter is our free tier that allows developers to build and publish simple apps that contain no more than
128k of compiled user code (IL), don't call out to native third party libraries (i.e., developers may not P/Invoke into C/C++/Objective-C/Java), and are built using Xamarin.iOS / Xamarin.Android (
not Xamarin.Forms). Xamarin Starter installs automatically with Visual Studio 2015, and works with VS 2012, 2013, and 2015 (including Community Editions)”.