Click enter a serial number next, select I Agree, then select Activate (in windows 8.1 windows 10 you should turn off Windows Defender. Entering an incorrect product key will cause activation errors and you will be unable to use your Autodesk software. Launch Autodesk Revit 2019 software to conduct Cr ck. It is important to ensure you are using the correct product key for your Autodesk product and version. The same version of AutoCAD is in both packages but the product key differentiates one package from the other. For example, installing AutoCAD 2017 as a stand alone product requires product key 001I1, but installing AutoCAD 2017 from the AutoCAD Design Suite Ultimate 2017 requires product key 769I1. Autodesk product keys are required to install Autodesksoftware and are used to differentiate between products that are sold independently and as part of a product suite.