are you using impulse or SDC to download and install windowblinds?.
did you download the program from a seperate link?
did you purchase windowblinds as a seperate program?.
if you use impulse or SDC to install windowblinds, providing that windowblinds is part of your object desktop subscription and not a seperate purchase then it should download, install and activate automatically.
if you purchased windowblinds seperately then the serial number should have been emailed to you. Use that number and the email you used when you purchased WB to activate it.
if none of the above work, send an email to support@stardock.com and they should be able to help you.
good luck mate