What can I do if my Chromebook is no longer eligible for Chrome OS updates?
Google provides automatic updates for Chromebooks to make sure the operating system stays current with the latest features. Once your Chromebook reaches a certain age (generally 5 years), Google may no longer provide operating system updates. To see when your device may stop receiving updates, you can check the Google Auto Update Expiration List.
You can keep using your Chromebook after it stops receiving updates, however, you will no longer receive security updates and some websites or apps may no longer work. At this point you may decide that you want to install a different version of Linux on your Chromebook, or upgrade your device to a newer model.