Ok, to to get rid of this counter I wanted to install the most current version. As the installation failed I uninstalled the old version using the deinstaller from windows and the Avast cleaner tool. Unfortunately the installation of the current version failed again. Re-installation of the old version (17.3.2291, build 17.3.3443.0) worked, but with the registration countdown. I tried again to update to the new, current version, which failed again.
I attached the installation log file. Maybe it helps...
It seems to fail at sending anything to the internet... obviously, as it hasn't an internet connection. This shouldn't be a problem for an offline installation...