By default, Metria CityModeler checks for updates each time it is started. You can turn on and off this functionality by choosing Help->Automatic check for updates. You may for example not want this check to be done if you know that you do not have an internet connection.
You can explicitly check for updates by choosing Help->Check for updates....
If there is a newer release a message is displayed as shown below. Closing the message will exit Metria CityModeler and launch your default web browser with the path to the Metria CityModeler update site. Follow the instructions on the web page to install the new release.
If there is no later update, you get a message that you run the latest version.
Figure 3.1: Information on a new update of Metria CityModeler