If you'd like additional users to have access to your organization's private repositories, you can purchase more seats anytime.

Note: Only organization members with the owner or billing manager role can access or change billing settings for your organization.

  1. In the top right corner of GitHub, click your profile photo, then click Your profile. Profile photo

  2. On the left side of your profile page, under "Organizations", click the icon for your organization. organization icons

  3. Under your organization name, click Settings. Organization settings button

  4. In your organization's Settings sidebar, click Billing. Billing settings

  5. Under "Billing overview", click Add seats. Add seats button in billing settings

  6. Under "Add seats", type the number of seats you'd like to add. Field to enter number of new seats

  7. Click Add seats.

Further reading