The Wayback Machine - https://web.archive.org/web/20210817112412/https://docs.github.com/en/billing/setting-up-paid-organizations-for-procurement-companies/renewing-your-clients-paid-organization

Renewing your client's paid organization

If your client's organization has a valid payment method on file, their yearly subscription will automatically renew. Billing managers can view and update the organization's payment method and subscription.

If you're not a billing manager for the organization, ask your client to have an owner of the organization add you to the organization as a billing manager.

Tip: Billing managers can also change the organization's number of paid seats anytime.

Updating your organization's credit card

In the upper-right corner of any page, click your profile photo, then click Settings.
In the settings sidebar, click Organizations.
Next to the organization, click Settings.
If you're an organization owner, in the left sidebar, click Billing & plans.
At the top of the page, under "Payment information", click Update payment method.
Under "Payment method", click New Card.
Under "Payment method", choose to pay with a credit card or PayPal.
Complete the payment information form, then click Submit.