Creates a checkout session to upgrade a subscription.
Bearer authentication header of the form Bearer <token>, where <token> is your auth token.
Subscription tier to upgrade to. "professional" is an alias for "pro".
free, pro, enterprise, professional "pro"
Billing cycle
monthly, yearly "monthly"
Seat quantity for licensed subscriptions
x >= 13
URL to redirect to after successful payment
URL to redirect to if payment is cancelled