The recent nags about the 50% sale are abnoxious. I get that you need to advertise but his sort of nag goes way too far. Most considerate vendors will provide a 'Do not display this message again' sort of check box. You do not.
I have used the free CCleaner for at least 10 years and discovered it was a great product, saving me lots of time over the manual procedures I created to do the same thing. I even purchased a copy a number of years ago to help support the cause. But I have 6 machines in use in my home and was not about to buy a copy for each of them, therefore I continue to use the free version. I don't have multiple accounts on our machines, at least no additioanl accounts that are used often or extensively, so I don't need the upgrade.
I put up with you offloading the routine updates to FileHippo although I find them very annoying. The dumb decision to push (force) Avast was a big mistake; reprimand the person who suggested that move. We, your long-time users, put up with those moves because we trusted you to continue to provide a quality, useful product. However tha nags are an irritant that may push many of us away, away for good. There are other quality (purchased) products on my systems that offer to do what CCleaner does but, to date, I have not used them, preferring instead to stay with CCleaner which I have trusted for over a decade, and have installed on dozens of client machines as well as for my family and friends.