Windows 10 RAM Upgrade Question

I am running Windows 7 64-bit Home Premium on my gaming PC. I know that this Windows will only take 16GB of my RAM when installed on my computer. I don't see the point why I need to upgrade to Windows 7 Pro or Ultimate Edition to increase or expand my RAM. When Windows 10 will be available, it will be a free OS right? Can it handle as much RAM unlike my current Windows 7?
