From https://www.reddit.com/r/Windows10/comments/j58y6f/no_longer_free_windows_10_hevc_video_extensions/
Don't waste a dollar on Windows 10's HEVC video extensions. You can actually get it for free. The reason why they made it a paid extension is because H.265 is a patented technology and requires anyone willing to implement it to pay for royalties. There used to be a loophole where you could get "HEVC video extensions from device manufacturer" instead, which is free, but they recently patched this loophole and decided to make it unavailable for install. However, there's another loophole they've yet to patch which allows you to get the same extension, bypassing this restriction.
Copy-paste this into the browser address bar: ms-windows-store://pdp/?ProductId=9n4wgh0z6vhq
There will be a popup that says "Install". Click on "Install"
The HEVC video extensions is ready to use. This can be very useful for Premiere Pro or After Effects as the Windows version doesn't come with built-in HEVC support by default and requires you to install this extension before you can use it.