When IDM is installed, it creates registry entries to track how many days of the 30-day trial have passed. A tool like this attempts to delete or modify those specific entries, tricking IDM into thinking it has just been freshly installed, effectively restarting the 30-day clock.
This occurs when IDM detects a previously attempted activation. Use the "Reset Trial" function (not the Register function) to clear the error state. When IDM is installed, it creates registry entries