Hi,

Well, in order to update Nintex you need a vaild software assurance. Your license shows, that this is expiring on march 27th (unless you renewed your license).

If you have a valid software assurance, you can download the new version of Nintex and just install it on any of your SharePoint boxes, just like the initial install. This will detect that Nintex is already installed and trigger an update.

Depending on the concrete version you might need to update the database schema i  the central administration of SharePoint.