If you find yourself needing more than 200 credits in a month, don't worry! You can always buy more with these easy steps or you can also refer and earn credits.
Click on "Account Settings" and click on "Account & Billing".
You can see available email credits along with their validity.
Scroll down to the section titled "Buy Credits".
Click on "View Plans".
Choose any of the 3 given plans according to your needs.
Fill in your billing details.
Select the mode of payment.
Enter your card details and click "Pay".