Find out how your revenue is spread across different subscriptions plans that you offer, for the last week.
Find out what subscriptions are bringing you more money each week and find out why the other ones are not so appealing to the customers.
Look at the landing pages you're using for each subscription, try A/B testing them or even ask for customer feedback.
If you're happy with the revenue split across different subscriptions then you need to monitor from week to week that the revenue ratio is constant and you are increasing in revenue.
A decrease in revenue will mean that your marketing efforts in the past weeks were not so effective and you need to see why your revenue coming from this business mode had decreased.