Can't update to Ccleaner pro

I installed the pro version and went to about and clicked register and put in my registration number. I put in the user name and it said the registration information I entered was invalid. Not sure what to do to correct the situation

See this support article about problems registering CCleaner, including if you get an error saying that the licence key is not valid:

https://support.piriform.com/hc/en-us/articles/204043844–Problems-activating-or-registering-CCleaner-Professional

Come back if that doesn't help.