The following message is returned When entering the license key and site message.
"Error Saving Key. Reason: Unable to validate license key. Reason: Unable to create license directory."
or
"Error Saving Key. Reason: The product was unable to save the license file. The most common cause for this error is that the user account has limited privileges and is unable to save to the required location."
Give user read and write privileges to the C:\Users\<your_user>\AppData\Local\ directory.
Note: User should be at least a Power User to use Toad.