It depends from broker to broker. Some brokers only charge if you trade in a particular month otherwise your brokerage is zero while others charge fully irrespective of you trading in a month or not.
Example:
Brokers like Prostocks and SAS Online's monthly plans are active on a calendar month basis which means monthly plans exist till the last date of the month. You only have to pay if you execute the trade in any particular month. If no trade is executed in your account for the entire month, then the brokerage levied will be zero.
