The Office 365 Autohosted Apps Preview program—a program Microsoft created “to determine how best to provide a friction-free deployment experience for creating apps for SharePoint”—ended June 16, 2014.
As a result, you’ll notice that the Visual Studio 2013 update 3, released August 4, doesn’t let you create autohosted apps and deploy them into your production SharePoint Online site.
Microsoft says Visual Studio will still support existing apps and that they’re not being shut down “at this time.”
Microsoft does recommend transitioning autohosted preview apps to provider-hosted apps, and offers a step-by-step article at MSDN.
Read the article on the Office Blog page “
Update: Autohosted Apps Preview Program Part 2” for more information.