If you already use SharePoint Forms for SharePoint 2013 and need to upgrade it to the latest version, download the .zip file from http://www.virtosoftware.com. Unzip the file and run setup.exe as it is described in the Installing SharePoint Forms for SharePoint 2013 section.
Note: it is highly recommended to exit License Manager before upgrading. If you need to use License Manager, run it after upgrading.
On the step check the box “Upgrade” and click “Next”.
Note: if you had activated the license while installing the previous Virto SharePoint Forms for SharePoint 2013 version, you do not need to activate it now.