If you need to upgrade a single license to a higher (Server) license or to a higher (Ultimate or EMS) edition, it's possible to purchase the upgrade at any time - please read the Upgrade page for more details.
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 or you can use Kentico Installation Manager to perform an automatic upgrade of your project.