How many IPs can I add to rules in the threat control panel?

The number if IP rules you can add in the threat control panel is variable based on the number of active zones on your CloudFlare account and the subscription level of each zone.

Each zone at the Free level of service is allocated 200 rules.
Each zone at the Pro level of service is allocated 1,000 rules.
Each zone at the Business level of service is allocated 2,000 rules.
Each zone at the Enterprise level of service is allocated 10,000 rules.

For example, if you have two zones at the Free level of service and one at the Pro level, the IP rule limit for your CloudFlare account will be 1,400 rules. It is important to note that these rules will apply to all zones on your account.