The link in the Reply #1 did not help:
Unable to activate Avast Cleanup after upgrading Avast free antivirus (uninstalling) to Avast Pro Antivirus (installing new and activating sucessfully).
Licence for Cleanup is seen in the activation menu, but after presseing "use this licence" button, it does not get Cleanup activated. The button turns into "proccesing scale" and nothing happens next. No error messages appear.
Any ideas what I may do to activate the Cleanup?