If you're running Windows 10 32-bit, you can use these steps to make the switch to the 64-bit version without spending a dime.
Windows 10 is available in 32-bit (x86) and 64-bit (x64) architectures, and if your PC is using a 32-bit installation, you can upgrade to 64-bit as long as you have a capable processor and enough memory.
Although both architectures include the same set of features, the 64-bit version of Windows 10 unlocks support of up to 2TB of RAM, which overcomes the 4GB of RAM limitation found in the 32-bit variant.
This additional access to memory enables you to run more apps simultaneously, and it improves productivity with memory-intensive tasks, such as video editing, virtual machines, and web browsing when dealing with a lot of open tabs. In addition, you can run x64 as well as x86 applications, something that it's not possible on a 32-bit installation.
Unlike upgrading from Windows 10 Home to Pro, switching from 32-bit to 64-bit doesn't require to purchase a new license. However, there's not an in-place upgrade path to switch, which means that if you're planning to move to a different architecture, you must perform a clean installation of the OS.
Full story from the WindowsCentral blog...