I'm starting to think you don't believe me or something...This will be the third time I've answered you - they send an email to the registered address.
It means you updated your IP address. Why are you making something that's working, so difficult?
This was also explained in a previous thread.
To be clear, you don't have to visit the NO-IP site daily. It seems like you're implying that. You just answer the email they will send in 21 days; and every month thereafter.