Maps for ASP.NET Web Forms
Legal Requirements and Authentication

C1Maps allows you to use geographical information from Bing Maps. Before using this service, you should check the licensing requirements associated with it. These licensing terms can be found at:
http://www.microsoft.com/maps/product/terms.html

How to Authenticate Bing Maps

The map surfaces provided by the C1Maps control (VirtualEarthRoadSurface, VirtualEarthAerialSurface, VirtualEarthHybridSurface) use the Bing Maps API. Usage of these online tile sources is not free for commercial use. You can learn more about using Bing Maps from the Microsoft documentation link below.

http://msdn.microsoft.com/en-us/library/dd877180.aspx

Using a Bing Maps Key in your code is the recommended method of authenticating your Bing Maps application using C1Maps. Bing Maps Keys do not expire, and a service request is not required to obtain a key.  Therefore, it is very easy to authenticate your application using a Bing Maps Key and the C1Maps control.