I do see text when I enter my Mac OS password - the instructions say I won't. CCleaner does not open as sudo and remains Free when I have purchased Professional.
Moved to CCleaner for Mac.
That sounds very much like something did not work correctly when executing the sudo command, as (as far as I am aware), you should not see any feedback when entering your password for this in any version of macOS. At most, you should see asterisks showing how many characters you've entered, but not what characters have been entered, specifically. I'd try it again, but if that still shows the same behavior, you may want to check with Apple Support to see if that's normal behavior in your specific version of macOS (it really shouldn't be, that's a terrible security risk!!!) and, if not, how it can be corrected.
If, as I surmise, something is not working correctly with sudo, then that would explain why CCleaner is not able to gain superuser permissions, explaining the rest of the issue quite simply.
johnccleaner, I thank you for your thoughtful advice. As I have very carefully at least five times gone through the process, and each time seen my password, I will check with Apple Support, as you suggest. I did have a problem that they just had a fix for yesterday. This, as you say is not something that should happen, and appears to be an Apple problem. Again, thank you.
You're quite welcome; it's not my first instinct to tell someone 'go find someone else to ask', but I know Sudo is part of the OS, so if it's not acting right, going right to the source seemed like the best option.
(Plus, to be truthful, my knowledge of macOS is hardly exhaustive, so I'd hate to tell you 'no, that's never the expected behavior' if indeed that is what you should be seeing. :) )
In any event, if that gets resolved and you're still having trouble registering, or Apple support tells you the Sudo behavior is not a problem, please feel free to take this up directly with our support team via our Contact Us form or by emailing support@ccleaner.com directly, or you can of course reply here as well.