Regardin windows serial key

[Rajat94]

My hp laptop come with genuine win 10 now i install window 10 agin but i forget my earliest wind key does now any way to know my key?

[Dudefoxlive]

Product keys are now a thing of the past when purchasing a new laptop. Your Windows license key is now stored in the BIOS of the machine and when you go to reinstall Windows fresh it will auto detect the key and activate once it connects to the internet. 

[WAWood]

@Rajat94

While what @Dudefoxlive is saying is true, if you simply want to keep a record of your product key, you can use this utility to find  it, decode it, and store it offline:  http://www.tenforums.com/software-apps/2577-showkey.html

Good Luck