The number of subscribed contacts in your Sentori account indicates the total number of emailable addresses that you have.
“Subscribed” is an overall status of the contact that indicates that you have permission to email them (assuming your list is compliant with our anti-spam policy). In addition to this subscription flag, you may also maintain separate subscription preference information (for example by using Mailing Lists).
The number of subscribed contacts is also used by us to provide billing for your account.