Your license can be managed in the accounts page related to your email address.
Here you can:
Change the edition of your subscription i.e. ENTERPRISE or ULTIMATE
Change how many license seats you would like to reserve for your annual subscription
Move from monthly (on-demand) to annual (reserved) subscriptions
See on-demand usage
View past invoices
If you have chosen to be invoiced annually, then you will be unable to manage your license edition and subscription details from the accounts page. In this case, please contact the sales team in order to make any adjustments to your account.