Question about windows 10 activation key when getting a new hard drive

[Mutantmidget]

Recently my is hard drive failed. Obviously I want to get storage but am not sure if I will need to get a new product key since It is a new hard drive.
I have no idea what the activation key for windows 10 was in my old hard drive.
My question is do I need to know my activation key when I reinstall windows on my new hard drive.
(I can get to the command prompt on my old hard drive but that is it)

 

[SchizTech]

Windows 10 re-activates on the same previously activated system without a key. If the system was legitimately upgraded to 10, came with 10, or had 10 installed with a disk and a key, the activation status is stored in Microsoft's activation servers (linked to the motherboard's unique hardware ID).

If you're re-installing from a disk or flash drive, there will be an option to skip the product key. When you go online it should automatically activate.