I think that you're still using a previous version of PDF Driver.
Now, the latest version is 7.83 R1, please download the installer at http://www.pdfwizard.com/eng/product/downdrv.asp.

1> Uninstall and deactivate your PDF Driver product and reboot.
2> Install PDF Driver 7.83, enter your serial number for enabling and activation as before.

After online activation, you can use PDF Driver product without any limitation.
Note: The activation process will NOT collect, use, or transmit any personal information.

If the problem still exists, please send your serial number to support@pdfwizard.com.
We will get back to you immediately after investigation.