Kathy, if you purchased OneCare during activation, the last step of that process is that OneCare receives the subscription credentials from the server. If this did not happen, something may have prevented the credentials from being received. Try clicking Check for Updates in OneCare. Also, check your PC date and time.
If it still shows you to be in trial mode, please contact OneCare support -
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve