Knowledgebase : CloudFlare > CloudFlare Pro Service
Absolutely! CloudFlare offers Free and Pro service on a domain by domain basis. So you can easily have both Free and Pro domains in one account.
Pro accounts are charged on a month-to-month basis. There are no longterm contracts. At this time, you can not pay for your account annually.
Your pro account will continue to the end of the current month's billing cycle.
Visa, MasterCard, Discover and American Express are accepted.