On default sites, the plugin can be updated on the Updates or Plugins pages in your back end, just like the free plugins from WordPress.org. You will be notified about new versions and can install them by clicking on the update link.
On multisite installations you need to go to the Tag Groups settings of a site where the plugin is active. Proceed to the Account page and click on “Install Update Now”.
Please note that updates are only available if you have an active subscription at Freemius.