I am currently running Big Sur 11.4 on my iMac but the CCleaner window is showing Mac OS X 10.16 iMac 17.1, Quad-Core Intel Core i5 @ 3.30GHz, 32.0GB RAM.
I also tried to purchase the current CCleaner Pro and after the Product Key was issued the downloader stopped working. I can't figure out where to enter my Product Key to get the CCleaner Pro to work. Anyone have any ideas to help me out?
![Screen Shot 2021-06-28 .jpg]()
Big Sur is both v10.16 and v11.#, which one you see depends on where and how you look.
It's for legacy/compatibility reasons, see this for a fuller explanation: https://community.ccleaner.com/topic/60444-need-help-understanding-top-right-corner/?tab=comments#comment-328971
For registering CCleaner if you already have a license key then go to Options>About and click on 'Upgrade to Pro'.
Enter your licence key and click on 'Register'.
See this article for more info or if you are having problems: <a href="https://support.piriform.com/hc/en-us/articles/204043844-How-to-register-and-activate-CCleaner-Professional" rel="external">https://support.piriform.com/hc/en-us/articles/204043844-How-to-register-and-activate-CCleaner-Professional</a>
(PS. I've removed the duplicate post from CCleaner Help and just left this one in the Mac section).