The mighty Mojang released a statement on how you can upgrade to Minecraft 10 for the sweet price of €0 (which roughly exchanges to £0/$0.)
Windows 10, Microsoft’s shiny new operating system, launches tomorrow. As announced at MINECON 2015 a few weeks ago it features a brand-new Edition of Minecraft. It is currently called Minecraft: Windows 10 Edition Beta and if you’re one of the 20 million(ish) players who already own Minecraft for PC/Mac, you get the new version for free. Completely free!
To download your copy, first log into your Mojang account. Next, click the “Redeem” button on your account page, sign into your Microsoft account, and follow the instructions that follow. That’s it! You’ll be playing Minecraft: Windows 10 Edition Beta in a jiffy. Minecraft: Windows 10 Edition Beta will be available to download in the Windows 10 Store.