Using license on multiple devices

CCleaner for iOS
1

What are the steps to use my current license on my iphone and ipad?

Thanks, Ted

2

currently pro for ios is not sold through CCleaner license you can only get it from apple themselves. At least this was true when i last checked

3

Multi-device licences (CCleaner Pro+, CCleaner Premium) currently cover Windows, MacOS, and Android devices.

At the current time they do not cover iOS devices.
If you want CCleaner Free for iOS then you have to get it through the App Store, and if you want purchase/upgrade it as Pro then you have to do that through the App Store too, it’s an Apple licencing restriction.

CCleaner Pro for iOS may get added to the multi-device licences at some time in the future, but that depends on Apple agreeing to it.