Will windows work if I rebuild my PC?

Curlymike

Note: PC not built yet, but this is just for reference.
I'm looking to rebuild my PC, as the other discussion I've posted talks more about. Basically, I'm replacing the motherboard and CPU and want to know if I can still keep my windows subscription without having to buy a new one. I made sure to link the key on my previous PC (now dead) to my Microsoft account, as they recommended. If I boot Windows 10 Pro (my subscription) off of a flash drive and use my old key, will it work? 
*Might need to speak to windows support about it, but I figured I'd check here too. 

Ian

Curlymike said:

Note: PC not built yet, but this is just for reference.
I'm looking to rebuild my PC, as the other discussion I've posted talks more about. Basically, I'm replacing the motherboard and CPU and want to know if I can still keep my windows subscription without having to buy a new one. I made sure to link the key on my previous PC (now dead) to my Microsoft account, as they recommended. If I boot Windows 10 Pro (my subscription) off of a flash drive and use my old key, will it work? 
*Might need to speak to windows support about it, but I figured I'd check here too. 

Was it a pre-built system such as HP, Dell etc., or custom-built?