To download the ISO copy of Windows 10, which is available in both 32-bit and 64-bit flavours, one needs to head over the Windows Insider Program page and join the Insider Program.
Whether you want to install Windows 10 Preview on a virtual machine or on a spare PC, you need the product key to complete the installation. Those of you have downloaded Windows 10 ISO image after joining the Insider Program, probably have noticed the product key on the download page.
Product key to install Windows 10
When you’re asked to enter a product key, please enter one of the following keys depending on the edition of Windows 10 you’re installing or activating.
Windows 10 Home: TX9XD-98N7V-6WMQ6-BX7FG-H8Q99
Windows 10 Pro: VK7JG-NPHTM-C97JM-9MPGT-3V66T
Windows 10 Enterprise: NPPR9-FWDCX-D2C8J-H872K-2YT43
These product keys can be used to activate all preview builds of Windows 10 that are officially released by Microsoft, which also means that the key might not work on leaked Windows 10 builds!