Here is how to get the Windows 8.1 ISO and create a USB install stick

Are you bummed that you can't get your hands on the Windows 8.1 ISO file since you don't have an MSDN or Technet account? Well, thanks to a simple little trick, you too, can join the cool kids and get your hands on the ISO to create your own install media. This trick is quite handy if you need to update many machines because without doing the following, you would have to download the Windows 8.1 files on each machine, with this trick, you only have to download them once.

The trick, which is actually quite simple and detailed below, and it allows you to create your own media to install Windows 8.1 at a later time without having to install a previous version of Windows 8 first.

Head over to https://windows.microsoft.com/en-us/windows-8/upgrade-product-key-only
Scroll down and click Install Windows 8 (This will trigger the installer assistant).
Enter your Windows 8, Windows 8 Pro or Windows 8 Upgrade product key, confirm that you will be downloading the bits for the version you paid for.

As soon as it starts downloading, close the installer assistant from the (X) in the top-right corner.
Go back to the Microsoft Windows upgrade page, click Install Windows 8.1, and download the newer installer assistant.
Run the newer install assistant.

When the download is complete, you can choose to install the OS right-then, or you can choose the option: Install by creating media. This option will allow you to create a USB/DVD media.