If you need to upgrade a single license to a higher (Server) license or to a higher (Ultimate) edition, it's possible to purchase the upgrade at any time later, without any extra fee, only for the price difference! The upgrade does not extend your current maintenance contract so your current period will not change. If you want to make an upgrade, please send us a message to sales@kentico.com.
If your maintenance contract is valid you will get the latest version for free as a part of your maintenance. If your maintenance has already expired contact our sales team at sales@kentico.com and they will recommend you the best way how to get the latest version.
You can find all necessary files for your upgrade here.