1. Download & Install Bitdefender.
2. Register My Bitdefender account
3. Boot into safe mode and use the trial reset to install the auto-reset function or to use the manual reset.
4. For autoreset: Restart/Shutdown Windows to reset the trial date. If you are using Windows 8 with UEFI bios, then you have to restart everytime you want to reset the trial date.
5. Enjoy!