As long as your Visual Paradigm license covered from maintenance it will entitle the upgrade to latest version. But in some situation you may found that your license do covered from maintenance but still no upgrade is available.
This probably caused by your account do have other licenses which still in older version and is already out of maintenance. To avoid compatibility issue in this situation the system will not automatically generate upgrade license for you which avoid some of your users upgraded to new version while the others still in old version. If you confirm the license in older version is no longer in use by any users, or they are belongs to another team where your work is independent with them you can then login to your Customer Service Center account and press the License upgrade is available button at the bottom right of the page to obtain the upgrade license.
After pressing the button the Upgrade Preview dialog will be shown with a list of the license which entitle for upgrade. Press Upgrade button to proceed.
And then the license covered from maintenance will be upgraded to new version.