Since you appear to have activated the subscription, you should first verify this by going to https://billing.microsoft.com to see your subscription status when signing in with the LiveID used for the original activation.
If it is reporting that it needs to connect to the Internet to complete activation, see this post:
Unable to Connect to Internet to Complete Installation
If that doesn't help, try removing OneCare completely from Control Panel/Programs and then run the cleanup tool:
Cleanup tool - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=828910&SiteID=2
Review the installation troubleshooting:
See this post for the KB article to troubleshoot install problems - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=1588602&SiteID=2
And then reinstall OneCare, subscribing/activating with the LiveID for your subscription. If that still fails, please contact support.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve
