Why did you post to the Expression Profile Feedback forum? That's the reason for the delayed response.
Did you purchase by clicking Subscribe in OneCare or did you purchase by signing in at the OneCare web site? If the latter, click subscribe in OneCare and sign in with the *same* LiveID you used to purchase the subscription.
If that does not resolve your problem, please contact support for help.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator