Monitoring Data Viewer Logins for ODK Aggregate

What is the problem? Please be detailed.
I was just wondering if it is possible to monitor which Data Viewers login to the ODK Aggregate server and when they do so. As part of quality assurance, our research supervisors are supposed to login to the Aggregate server to view data and check quality. However, we would like to be able to monitor this activity to make sure that they are actually doing this. Is there a way that we can check on this, possibly through the App Engine logs?

What ODK tool and version are you using? And on what device and operating system version?
We are using the ODK Aggregate built on the Google App Engine


User log feature is not available on ODK Aggregate and I don't think you can get that information from App Engine.