Windows keys are in BIOS with a HOME or PRO windows Genuine label. There is no reason for the user to have the key. When you clean install windows 1809 you tell it that you do not have a key and it will install. You do have to tell windows the correct version however. If you tell it you have WIN10 PRO and you only have WIN10 HOME key in bios it will not activate.   Showkey plus will show the bios key if the machine is online and has touched microsoft at least one time. It will also show the key that was used to install on systems that are older that do not have a key in bios.  I DO NOT RECOMMEND Getting this app ANYWHERE but on Github.  Several sites inject malware into copies of this program. [URL]              
I purchased a Inspiron 15-5558 with Windows 10 pre-installed.  It was delivered on the release date (July 29th).  There is no Windows sticker or product key anywhere on the laptop, I even looked under the battery.  Where can I get the code?
Windows 10 Product Key?