It all depends. If you don't have a physical product key or label with it on your pc somewhere (usually on the bottom of it). Some manufacturer's like Asus now embed the product key inside the motherboard itself. Thus, you need to clean install whatever version of Windows your pc came with and then upgrade to whatever you're using now afterwards. I'd still let the Windows Upgrade Program for 8 or 8.1 make the bootable flash drive for you. Just make sure not to cchoose the Install Now option. I forget what they call it in each, as I made my Windows 8.1 flash-drive back at the end of November. That flash drive also worked on my notebook, but I had to do a 2nd clean install. Reason for that was, that I downloaded and made the Windows 8.1 flash drive on my desktop pc. My desktop pc has Windows 8.1 Pro with Media Center x64 on it. My notebook has plain-Jane Windows 8.1 x64. The flash drive installed Windows 8.1 Pro with Media Center on it. My notebooks product key is just for regular Windows 8 and can only be upgraded to regular Windows 8.1 x64. Thus, I coped my Windows 8 dvd files onto a 2nd flash drive and clean installed Windows 8. It picked up the product key off of the notebook's motherboard and activated itself. I then ran Windows Update until none were found anymore. I then opened the Windows Store and got the Windows 8.1 upgrade and installed it. I hope that wasn't too confusing. (P.S. Make sure the flash drive you use has at least 4.0 GB's. of free space on it.