The number of source IP rules that you can add depends on the Redis Cloud plan that you purchased. For example, the 1GB plan allows up to 8 source IP authentication rules. These rules can contain either IP or CIDR.
In case you require more source IP rules than your plan entitles you with, you can see the different plans and the maximum number of source IP rules that they support here.
You may change your subscription at any time by going to My Resources ==> Manage ==> Change
Note that only account Owner can upgrade/downgrade the subscription