This article https://support.ptc.com/appserver/cs/view/solution.jsp?n=CS264270 and the blog post provide information on the technical changes in Thingworx 8.0, New Technical Changes in ThingWorx 8.0.0
Here are some common questions and answers in regards to the change.
We do have some requirements for highlighting "repeat offenders". In 8.0, one can query the logs to find those app keys. We don't log the app key id, only the app key name.