As I said I couldn't validate the key that would have to be done by Alwil, I'm just an avast user like you.
The key looks valid, at least in the right format, but if it weren't valid it would say and you wouldn't be able to update.
I suggest you remove your unique key to avoid its harvesting.
You need to check that your Logging level is set to at least record this information, Program Settings, Logging, ensure that the slider is opposite Notice then every thing above that will be logged.
If this doesn't resolve things, try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this.
If that doesn't work try, uninstall, reboot, install, reboot.