Wenn ich heute den CCleaner kaufe muss ich sofort aktivieren oder kann ich erst wenn mein altes Abo abgelaufen ist, die Aktivierung durchführen
It sounds that you want to extend your licence rather than buying a new licence with a different licence key.
If you renew your subscription/licence then the new time will get added to your remaining time.
When is your current licence due to expire?
It should renew automatically, unless you have turned that option off.
If you buy a new licence it will be a seperate licence.