Hello Stephan,
It depends on the way you receive our products.
When you make a purchase on our website. You receive a product together with the license key right after the purchase. Use this key to activate your product and receive updates the normal way via Dashboard.
When you make a purchase on another marketplace you receive a product only. You will receive a notification about an update when we submit a new version. It depends on the marketplace notification system. For example themeforest has a standalone plugin to update all products you have purchased via your purchase key.
Each theme we develop has a bundle of built-in plugins. These plugins are updated together with the theme. You will see a message in your dashboard that some of the recommended plugins should be updated right after you install and activate a new version of the theme.