问题
I used the Apple MigrationAssistant to migrate to a new machine, and now MonoTouch won't launch my app in the simulator because it says my license is not valid. Following instructions in other posts here, I removed my license file and re-ran the setup, but that just told me that everything was installed and launched the app with the same problem. So, I completely removed MonoDevelop, and re-ran the setup. It dutifully downloaded MonoDevelop and installed it, but never gave me a chance to activate, so I'm still stuck.
回答1:
http://support.xamarin.com/
Look at the box that says "Product Download and Activation Self Service" - login there to re-download the full licensed version of MT. There are also some tools to deal with reactivating licenses.
If all else fails, contact support directly.
回答2:
Contact support@xamarin.com, they can help you.
来源：https://stackoverflow.com/questions/11249568/how-do-i-reactivate-monotouch