You can view or upgrade the existing billing plans for your workspace. To do this:
In the left navigation, go to 'Settings'.
Under the 'Plan & Billing' tab, you can view the current plan and expiry dates.
Click on 'Payment Details' to add your payment information which is used for the plan subscription.
Get additional seats for account
Navigate to Settings > Plan & Billing.
Click “Update Subscription”, on the pop-up you can increase the seats.
Click “Purchase Subscription”, upon successful transaction the changes will be reflected and for an increased number of seats the invoice shall be raised on a Pro-rated basis, and for the decreased seats the pro-rated amount will show as a credit balance which will get adjusted in the future billings.