To manage your subscriptions, click on your account in the upper right-hand corner, then select Account Settings.
From the left navigation, select Subscriptions & Billing.
Under the Subscription Management section, click on the Add Subscriptions button.
A box regarding subscription management will appear, prompting you to enter the total number of subscriptions that you would like to add and asking you to verify your payment method for these subscriptions.
Once you have entered in the number of new subscriptions that you would like and have verified your payment method, click Confirm.