But I think what David and you are saying is that there's a limit only if you're using the free version and they suspect you of commercial usage — right?
That being said, while I have seen the 5-minute limit enforced in the past, I have also seen it ignored even in situations where it is clearly commercial use (e.g. a domain-joined computer remoting into a Windows server). I've also seen the "commercial use suspected" notice and the session was not limited to 5-minutes.
So I guess Teamviewer's algorithms for how they detect commercial use and enforce sessions is somewhat... fuzzy.
Incidentally, If you use it to provide tech support to other people, even inside your own organization, Team Viewer Considers it Commercial use.