This adapter library for "ProjNet" (which is the name for NuGet version 2.0 but the name of the previous NuGet version 1.4 was "ProjNet4GeoAPI") 
is licensed in the same way as the adaptee library itself.

This means that the license is GNU Lesser General Public License v2.1.

https://github.com/NetTopologySuite/ProjNet4GeoAPI/blob/develop/LICENSE
https://raw.githubusercontent.com/NetTopologySuite/ProjNet4GeoAPI/master/LICENSE
https://github.com/NetTopologySuite/ProjNet4GeoAPI

https://github.com/NetTopologySuite/ProjNet4GeoAPI/releases
> 2.0.0
> Release of ProjNET without GeoAPI.
>	Now targets .NET Standard 2.0 only
>	GeoAPI references removed; the relevant useful stuff has been moved inside this package (namespaces updated).
> ...

NuGet ProjNet 2.0.0
https://www.nuget.org/packages/ProjNet

NuGet ProjNET4GeoAPI 1.4.1 (the previous version of ProjNet i.e. the name has changed)
https://www.nuget.org/packages/ProjNet4GeoAPI

