The technical press constantly warn against using any type of 'registry cleaner' programs, as there's a potential for them to do more harm than good. However they occasionally admit that there might be some point in using CCleaner and/or Glary Utilities. Both programs come in free versions (which only 'run on demand') and their 'Pro' equivalents (which 'run in the background').
If you're determined to have such a program running in the background, the full version of CCleaner costs £14.95 for 1 year's subscription
https://www.ccleaner.com/
or Glary Utilities Pro costs US$19.97 for the same period
https://www.glarysoft.com/store/
While I like to have the free versions of both programs available on my PC (just in case I might ever need either of them), I can't really see any point in paying for the full versions.