You can’t purchase octaedit right now. The creator, Rusty, is busy dealing with being alive in 2020, and doesn’t have the time to help onboard new users or provide support for v1 at the moment. The latest release of v1 is now out of date with the current octatrack os. Rusty is still working on v2 when they can and will notify people in this thread when it is available. Your options are to hang tight, or try and find someone willing to sell you their v1 license.
I missed a license going recently and I am very much bummed out about that, but I think the best thing you can do right now is work out how to do what you want without it (most(?) things in octaedit are doable with OT and a computer, although some things will take you muchhh longer), and keep an eye on this thread for further updates from Rusty.