Go to https://cloud.digitalocean.com/apps, click on your app, and click on the Insights tab. By default you will see insights such as memory and CPU usage for all of the active resources of your app. From here, you can click on a resource to filter insights by resource.
You can use the drop-down to change the date and time range for which insights are being displayed. You can also click the “refresh” button to retrieve new insights that have become available since the page was initially loaded, and use the drop-down to the right of the “refresh” button to schedule automatic retrieval of new insights at the given time intervals (e.g. every five minutes).
Additionally, you can create alerts for your app and its resources.