You can add domains and users to. your account. 

The scan crawls new domains if the number of pages does not exceed your subscription.

For more information and full instructions on how to add domains and users, read: 

• Add, edit, or remove a domain
• Add, edit, or remove users

If your current plan does not support the number of domains that you want to add, select Contact support in the Help menu to start a chat, or email Acquia Support.