You can retrieve your purchased serial number at any time from the link at http://www.bigoven.com/help.aspx -- also, the latest download is at http://www.bigoven.com - click on "Software" and then "Download".
If for some reason the automatic lookup of your serial number cannot find your purchased product, please email our support team (support at bigoven.com) with the email and full name you used for purchase, and we'll be happy to look it up. Thanks!