I want to know if I can add my new Ccleaner 7 on my PC, to my mobile without having to pay for it again
We moderators have been given no details about the CCleaner 7 beta version for Windows.
I only found out that it existed ‘in the wild’ earlier today.
AFAIK it is not for sale yet and is only available by invitation from within the current CCleaner Professional.
To answer your question about Android - If you have a muti-device (ProPlus, or Premium) licence then it can be used to activate CCleaner Android: