How to I transfer my current pro license to a new computer?
Simply install CCleaner Free on the new computer and then Register/Activate it as Pro using your existing licence key.
You can download an installer from here: Download CCleaner builds | CCleaner Portable, Slim, and more
Once downloaded just double-click it to install CCleaner Free.
Then open the new install and enter your licence key to register it as Pro.
Unless you have a multi-device licence (ie. CCleaner Pro Plus, or CCleaner Premium) then you should uninstall CCleaner Pro from the old machine. You could then install CCleaner Free on it.
They do recognise that people get new machines and so allow the key to be used more machines than the licence covers for a while.
(However they will notice if a key is being used longer term on more machines than that key is valid for, and will then invalidate that licence key for breach of terms).
Thanks for the prompt reply. I will proceed per the above. Steve H.