CCleaner 7 is now the ‘Official’ version, it is replacing CCleaner v6, if your v6 was Pro then your v7 should still be Pro.
I have no idea why it would try to do that, other than there being a programming bug of some kind.
As usual we haven’t been told about the release, or about how the update should work in different scenarios.
I do know that CCleaner 7 creates it’s own programme folder at
“C:\Program Files\Piriform\CCleaner 7”
and the install appears to remove the “C:\Program Files\CCleaner” folder that v6 uses.
If you are having problems activating CCleaner as Pro then see: How to Roll Back from v7 to v6.39