Curated billing plans are priced on the total number of subscribers across all of your publications. The monthly quota is 31 times the maximum number of subscribers for your plan.
For example, if you are on the subscription plan for 2,500 subscribers your monthly message quota will be 77,500 messages/month. This will allow you to publish at the frequency of your choice, whether that is monthly, weekly or daily.
Monthly quotas do not carry over to subsequent months.