2 CCleaner Pro accounts into 1

About a year ago, I installed CCleaner through the Google App store onto my Samsung phone and upgraded to the Pro version, membership paid annually through Google Play Store. Prior to this, I had installed the same onto my Samsung Tablet, BUT through Google Play Store with a different Google Login (my kid uses the tab mostly). Recently, I realized I have been paying for 2 Pro versions every year, so I let the Membership for the tablet expire, and I want to add the current one on the tablet (Since CCleaner Pro allows one membership for two devices). I am wondering what steps to take for a successful install of the CCleaner Pro (that I currently have a paid membership for) onto my tablet to replace the expired one? My thanks in advance for any help offered!

Short answer:
You can use a CCleaner for Android licence on any Android device (including multiple Android devices) simply by logging into the Google account that the licence is registered to.

Longer answer:
There are 2-ways to purchase a CCleaner for Android Pro licence.

You can purchase it though the Google Play Store.
You can purchase a multi-device licence from CCleaner.

If you have purchased CCleaner for Android through the Play Store then it is Google who administers it.
CCleaner themselves have no record of your purchase in the Play Store, you do not have an account with them. Instead your CCleaner Android is linked to your Google account.

I’m not sure where you got that from but it isn’t strictly corrrect.
A CCleaner Pro licence is valid for 1-device (1-PC or 1-Mac), a CCleaner Pro Plus licence is valid for 3-devices (mix of PC, MacOS, or Android), a CCleaner Premium licence is valid for 5-devices (mix of PC, MacOS, or Android).

(There is also a seperately licenced CCleaner for iOS devices - at the moment that is only available through the Apple Store, it is not included in a multi-device licence).

CCleaner for Android however is a bit of a special case.
CCleaner Android is licenced to your Google Account and not to any particular device.
Whether you have purchased a multitdevice licence from CCleaner or purchased CCleaner Android through the play store, once you have registered it to your Google account it is your Google account that is licenced/authorised to use it - on any Android device that you are logged into with that Google account…