For monthly plans, your credit card is charged when you sign up, and then every month on your renewal date.
For example, if you subscribe to a paid plan on December 15th, your account will automatically renew again for the next month on January 15th, and so on.
View Renewal Date/Billing Details:
1. Click on your email in the top right corner of your screen:
2. Click on your 'Account' tab then select the 'Usage & Billing' section.
3. the Renewal Date will be listed under the 'Usage' Section of your Usage & Billing page.