Automatic purchasing refills your account balance when it goes to 5 credits or fewer. This ensures you never run out of credits while you`re using the service. You are able to opt into this feature when you make your first purchase. You can enable or disable this on the payment window when you`re selecting a package to purchase. Select the credits tab and click on the “buy more credits” button. Click on the checkbox to enable/disable automatic purchasing. You can also do this at the bottom of the “profile settings” page. Click on the arrow pointing to the bottom of the screen next to the portrait icon. Select the “My Profile Settings” option. You will find an option to enable or disable automatic purchasing at the bottom of the page.