If you cannot afford a key, you can continue using Windows 8.1 unactivated. The limitations are minor:
The direct reality is that . If you don't already own a valid license for Windows 8 or 8.1, you cannot legally purchase one from Microsoft. As a Microsoft support representative stated, "Microsoft no longer sells 8/8.1 in any edition. You will have to take your chances online. Warning: You do not buy a Product Key by itself, as they are normally stolen/pirated". windows 8.1 product key github