Can we use the same license key for ccleaner for windows?
Unfortunately not.
It’s an Apple licencing restriction.
(They don’t want to share with anybody).
It used to be the same with Android but negotiations mean that CCleaner Android is now covered by the multi-device licences.
The same may happen with iOS in time, but Apple can be funny about such things as I’m sure you know.
As it stands you can only get a licence for CCleaner for iOS from Apple, and it only covers use on iOS.