I cannot register my valid visa card to make payment.
Welcome to the Cloudflare Community. 
Questions about billing will need to be resolved by the Customer Support team and cannot be resolved on the Community.
To contact the billing team, please submit a new support request from your Cloudflare account directly through the Cloudflare dashboard. Visit https://dash.cloudflare.com/?to=/:account/support and choose Billing. Please share your ticket number here so that we can track it.