When viewing a membership in your Single account, you'll see a number of different metrics and stats towards the top of the main page. Here's what each one means:
This one is pretty self explanatory - it's the total amount of customers that are currently subscribed to that membership. This accounts for all tiers and terms within the membership.
This is the total number of current members who have also purchased products or content that are gated (exclusive/membership-required) by the membership.
This is the total monthly amount of membership revenue being earned. Something to note here: If a customer is subscribed to a membership term that's longer than a month, even though the full membership term price is paid up front, it is divided up across the number of months of the term when calculating this number. For example, if a customer subscribes to a 6 month membership term that costs $60, although the $60 is collected up front at once, the amount added to the Monthly Revenue total would be $10 ($60/6 months = $10 a month).
Monthly Gated Revenue
This is the amount of revenue brought in by the sale of products and content gated by the membership over the last 30 days (not calendar month).