Among other things the ESBN number reflects your unique copy of Activ E-Book (the first 5 digits are your Activ USER number), so every eBook you create is identified with your "brand". Also a different ESBN number will generate a different Password ID number on a given computer.
For practicle purposes every new eBook you create should have a new ESBN number to ensure each eBook needs a different password.
By the same token, If you publish upgrades to your eBook and you don't want your present customers to pay again... make sure that the ESBN number stays the same.
With any business, it is up to the individual owner of said business to ensure the success of the business. You may make more or less than any sample figures or results that might be quoted on our web sites or other publications. All business involves risk, and many businesses do not succeed. Further, Answers 2000 Limited does NOT represent that any particular individual or business is typical, or that any results or experiences achieved by any particular individual/business is necessarily typical.