If instructed to reactivate Data Workbench, you can do this in two ways:
Activate via the Administration Section. If you have access to open the Data Workbench application, you can reactivate by going to the Administration Tab --> Then Click on the "Activation Wizard" button highlighted in red below.
Activate via the Diagnostic and Configuration Utility. If you cannot access the Data Workbench application until you reactivate, you can activate by going to the Start Menu--> Programs --> Quadrate--> Data Workbench--> Diagnostic and Configuration Utility. Then click on the "Activate License" button highlighted red below.