We have ArcGIS license manager installed on the same machine that has ArcGIS Enterprise Portal and clients get their ArcGIS Pro licenses through it. The license manager service randomly fails and clients get this message.

When you log into the server and look at the License Server administrator, it will say that the License Server Status as not running. When you click on the Start button, nothing happens. When you open the Services console, ArcGIS License Manager and Flexnet License Manager Service status says running. Both services are running under Local System account. We then have to restart the ArcGIS License Manager service and the Flexnet License Manager service, then the License Server adminstrator will show the stratus as running without having to click the start button.
The problem then goes away for a few days then reappears. Both services are set to automatically restart after failure but does not seem to make any difference. The License Manager is running on a virtual machine on Windows Server 2019.