My notebook keeps asking for product key for preloaded MS office 2010.

[vatsa]

Whenever I open a excel sheet it asks for product activitation . It was preloaded in my Hp Envy notebook. 

[mkaafy]

Are you sure it wasn't a free trial? Microsoft Office is usually sold separately. Please check your laptop model specifications page on hp website and this link also:

https://support.hp.com/si-en/document/c04867233

[WAWood]

@vatsa 

Is this a NEW PC, that is, less than a year old?

IF that is the case, it most certainly would NOT have come with Office 2010 (which is nine years old, now) and instead, would most likely have come with Office 365 -- and as @mkaafy indicated, that would have been a Trial version -- one that expires and can not be activated as a resulkt.