Trial version expired and switching back to the free version
So from the rough tracing I've done from what I can tell Teamviewer is phoning home and the Teamviewer servers are logging MAC address'. Sometimes incorrectly so a simple ticket to TeamViewer should allow you to flick back to the free version.
Having tested on a corporate license. If you have access to the management console, as soon as you distrust the device that was signing in with the license it flicks back to the free version. I'd assume if you didn't have access to this and weren't abusing this, then again, a simple ticket would allow TeamViewer to surely remove the MAC they have registered for you.
The question then is, why isn't this happening at uninstall? Surely this would come under the new EU GDPR law. So once you've uninstalled TeamViewer from your machine, you could argue TeamViewer have no legal reason to keep hold of your MAC address anymore so under GDPR should be deleting this info.
Does anyone from TeamViewer know if this is the case? Obviously we understand you can't fully disclose the way TeamViewer logs a devices as corporate or free as others may try to find a work around. But equally, if MAC address information is being kept centrally at TeamViewer HQ to manage this, then aren't people allowed, under GDPR, access to the data you hold on them and then under the Right To Be Forgotten section request that this data be removed?