No MSDM tab = no product key. If the system is meant to have one there is a fault with the mainboard (I have seen this a few times but it is very rare). You will need to call Dell Technical Support if the system is in warranty to have it replaced as the key is now considered hardware. The system will work fine otherwise. If you have no warranty you'll need to purchase a new Windows license or you could install Windows 10 Technical Preview and hold out to see if you are upgraded to Windwos 10 for free or for a discount.
Hey there, I've been trying to reinstall Windows 8 onto my PC while using the original key as my hard drive stopped working. When trying to use the Dell installation media, the Windows installer prompts you for a product key no matter what. I've loaded the BIOS defaults and tried booting the disc from Legacy BIOS mode as well. Any Ideas?  Thanks Hitik
Windows 8 Install - Won't Read OEM Licence Key From BIOS - Dell XPS 8500