Good morning. I have a new computer. How can I transfer my CCleaner license from my old computer to the new one?
Regards 
You can transfer your key to a new machine quite easily.
On the new machine download CCleaner Free from here: CCleaner - Download Builds
Double click the downloaded installer to install CCleaner Free, and then activate it to Pro by entering your existing licence key in Options > Licence Key.
You can see your existing key in the Options > Licence Key in your current CCleaner Pro on your old machine.
Once you have activated CCleaner Pro on the new machine then, unless you have a multi-device licence, you should uninstall CCleaner Pro from the old machine.
Thank you very much for your help. Everything is clear