You can transfer an expired license to another computer. You can Deactivate the license in WebDrive on the older computer, and then Activate the license on a different computer. The exception would be that WebDrive Version 10, for example, is not compatible with Windows 10, so you would likely not want to transfer that license to a Windows 10 computer, although it will install.
If you need access to the download for the older version, you can find them here: http://southrivertech.com/download-fully-functional-old-software-versions/
If you do not have access to the old computer, you can login and manage the activation directly by logging into this website using the Registration Code (license) and the email address associated with the purchase: http://activate.southrivertech.com/CIS