You will have a free 14-day trial period to explore Mailytics with absolutely no commitments.
When creating your account for Mailytics you will be prompted to select a subscription and a payment plan however you will not be required to enter any of your billing info at this point. Though once the trial ends you will need to provide us with your billing details or else your account will be deactivated until you do so. Once you have added your billing details, then after the trial ends you will be billed according to the subscription and payment options you chose during registration.
Add your billing details at any time, just access the Subscription Settings page found at Settings > Subscription, and then under "Billing Details" you will see the option to "Update Card Details".