Since January 2015 all version of CubeCart are now open source and 100% free. If you are seeing this page under "Upgrade Required" in the admin control panel of your store you can unlock all features by upgrading to the latest version. It is possible to get the latest version in the download area of our site.
If you would like official CubeCart staff to upgrade your store please take a look at our "Technical Support & Management" plan. We have upgraded hundreds of customers stores and always take full backups before proceeding with any work at all.