If your organization is using the legacy per-repository billing plan, you can switch to per-user pricing at any time.
In the top right corner of GitHub, click your profile photo, then click Your profile.
On the left side of your profile page, under "Organizations", click the icon for your organization.
Under your organization name, click Settings.
In your organization's Settings sidebar, click Billing.
Under "Plan", click Upgrade.
If you're upgrading from the free plan, under "Plan setup and duration", select a billing plan.
Optionally, if your organization account is owned by a business, select This account is owned by a business, then type your company's name.
Choose whether you want to be billed monthly or yearly.
Review the information about the charge and your billing date, then click Upgrade your plan to finish upgrading your account.