To update your billing information inside Tick, the account owner will need to login and go to "Settings" in the navigation. Please note that only the account owner is able to see and access the settings for your account.
Once inside the settings, click on "Billing" and you're able to update your payment details from there.
Note: If you're an Admin and need to find out who your account owner is, you can do so by going to "Users," and finding the name highlighted in yellow.