To see the amount due on your next billing date, start by navigating to your billing portal by clicking the user icon in the upper right corner of your screen, then selecting Billing from the dropdown menu.
Alternatively, this may also be accessed through the sidebar:
For customers on legacy plans, click "Edit Current Plan".
For customers on the current pricing plan, click "Update subscription".
Your "Next Renewal" amount and date will be displayed at the Summary part of this section:
On the next page, you can increase your Rank Tracker or Site Auditor totals as well, which will increase the renewal summary: