As Server Admin, you can configure the upgrade your self-service instance. Navigate to the Upgrade instance form in the Server space and configure the auto-update settings.
For subscribing to the latest stable release and having your instance upgraded automatically every time a new stable version of Squirro is released, you can choose the settings as shown in the image below:
...
This page can now be found at Upgrading an Instance on the Squirro Docs site.