I am also unable to update CCleaner Pro from 5.52.6987 to 5.55.7108. My registration is current and won't expire until mid-July 2019.
It seems to download ok, but then while unpacking/installing, give this error message:
Error opening file for writing. c:\ProgramFiles\CCleaner\CCleaner6.4.exe
Retrying doesn't help, and if I -Ignore- , it next gets hung up at
CCleaner\branding.dll