It is important to understand how Drip compiles your bill for any given billing cycle. Knowing how this works will help you better understand the amount you're charged.
Our billing works on a high watermark system, which means that you will be charged for the highest number of active subscribers in your account for the billing period and not the number at the time of billing. Although each invoice is for your next month of service, the cost is based on your previous month’s usage.
This high water mark system might be easier understood using a metaphor. Imagine your account as a large bucket and each subscriber as a cup of water. Every time a new subscriber (cup of water) is added to the bucket, a line is drawn on the side of the bucket to indicate the current level of water. If the bucket has 20 cups of water in it and five are removed, though there are only 15 cups of water in the bucket, the line indicating that 20 cups of water were in there still exists. The highest line drawn during the billing period dictates what plan level the account is charged under at the end of the billing period.
The easiest way to stay up to date with your current billing period is under Settings > Billing > Billing Info in your Drip account. You will also see information regarding your payment history and how to cancel your subscription.
You will see your plan type, usage and end date for your current billing period:
Note: The screenshot above is just an example. You will see your current usage details when reviewing your own account.