ActivInspire can be downloaded at home from http://www.PrometheanPlanet.com/ActivInspire.
You will need to have an account on Promethean Planet if you do not already have one which will enable you to download.
You do not require the serial number of ActivInspire or any Promethean Hardware in order to download the software, only to upgrade to the professional edition.
I hope this information helps.
Promethean Technical Support