I never had this problem before! We, my family and friends, work privately with Teamviewer a long time. No problems and all the time with the free-version.
Now, our Teamviewer installs show "trial version, 5 days left", what should we do? We only use Teamviewer for our own computers, I am "sort-of" the wizz-kid (not bad at age 64) and help them if things go wrong. We have 4 Windows pc's in our group and 1 Linux pc.