When a Check for Updates is triggered, it connects with the Malwarebytes servers to check for the latest protection updates and product version. If you are not running the latest Malwarebytes product version, an alert displays informing you an upgrade is available. You may receive an Upgrade Available alert for both Malwarebytes Premium and Free version on Windows device.
Malwarebytes for Windows Upgrade Available alert
Clicking the Install Now button starts the Upgrade process. For further instructions, refer to Upgrading to the latest version of Malwarebytes for Windows beginning with Step 6.