You can upgrade to a higher level license at any time without penalty by paying the difference between licenses.

To upgrade to higher level license

1. Login to your Client Area 
2. Go to My Licenses tab
3. Select the license you want to extend support and upgrade on
4. In the Actions section under Upgrade license to select license you want to upgrade to and click  Upgrade button
5. This takes you to the KBPublisher purchase page where you can purchase an upgrade