Beginning with release 9.0, the GPReg DLL is automatically installed and registered when either Microsoft Dexterity or the Microsoft Dynamics GP client is installed. You can find the DLL in the following location in a standard install.
C:\Program Files\Common Files\Microsoft Shared\Dexterity\GPReg.DLL
If you are using Microsoft Great Plains Release 8.0 or earlier, you will need to obtain the GPReg.DLL from technical support. Once obtained, to use this DLL in your applications, you need register the DLL by using Regsvr32.exe. If you will use this DLL in your application, also make sure that you distribute and register the DLL with your third-party application.