If the activation reminder is ignored and Windows 7 continues to be not activated, the “Activate Now” message will be presented daily until the 27th day. After 27 days, the message will pop up every four hours. On the 30th day, the frequency of the message will increase to once every 60 minutes.
If Windows 7 is not activated within the grace period, a bubble message will pop up every 60 minutes. Desktop will be set to plain black background (with auto reset every hour even to detect any change in background wallpaper) with persistent desktop notification that Windows is non-genuine. Reminder to activate will also be displayed upon logging on.
BTW, what prevents you from activating?