Why is Visual Studio 2015 community asking for authorization?

Question

visual studio

Downloaded VS 2015 along with Unity5. Now on startup it says (30 day trial expired). And it asks for authorization through a Microsoft account for activation.
Actually why, if the Community version is free?

Answer 1

These are the terms of use.
After authorization, you can continue to use. It will be enough to specify email . It's free.
Registration will allow you to sync between devices.
Through Visual Studio Team Services , you can participate in the development of collaborative projects. In particular, it is possible to work with the code in the browser on the site www.visualstudio.com . Everything is ready, so to speak, out of the box.

Answer 2

For example, then to synchronize the VS settings with the cloud.