To build NServiceBus just open NServiceBus.sln in Visual Studio.
You'll find the built assemblies in /binaries.
If you see the build failing, check that you haven't put the source of NServiceBus in a deep subdirectory since long path names (greater than 248 characters) aren't supported by MSBuild.
NServiceBus is licensed under the RPL 1.5 license. More details can be found here.
LightInject is licensed under the MIT license as described here.
LightInject sources are compiled into the NServiceBus distribution as allowed under the license terms found here.
SimpleJson is licensed under the MIT license as described here.
SimpleJson sources are compiled into the NServiceBus distribution as allowed under the license terms found here.