DriveWorks Express is a design automating tool and is included in every license of SolidWorks. It makes everyday design tasks easier by helping you create multiple variations of Solidworks Parts, Assemblies and Drawings quickly without having to alter the dimensions, features, etc individually.
The add-in is tied to your serial number for SolidWorks, and you will need to have a MySolidworks account ready. You can access this by:
Tools > Express Products >DriveWorks.
Click on the link mysolidworks.com/xpress
Login to your MySolidworks account
Copy the serial number from the website to the input box in Solidworks.
Watch the video here on an example of DriveWorks at use