ooops!!! I’ll fill that out right now and link to it here.
In a nutshell, as Steve mentioned, you should have received two emails from Paddle:
subject: Your order: Hook Pro (or Hook Essentials)
subject: Your Hook Pro Paddle.com Order
the latter contains a License Key URL. That URL loads in browser which then asks for permission to invoke Hook. Hook will then activate your license.
License emails (in #2 above) expire after a couple of weeks, after which they need to be resent. I’ve asked the development team to increase their life.
Using Hook, I also linked the web page to its .txt file source (stored on Finder, and in a revision control system).
While writing the web page and my reply, I used Hook to navigate between these three docs.
That means in the future when I revisit the help page, I can quickly navigate back to this forum post about it, and vice versa. And I can quickly get to the Markdown source. (We keep a Markdown source for almost every blog post and web page we publish on the website. That way we can write with the full power of a macOS desktop editor, rather than in the crummy confines of WordPress.)
Because my current reply was so long, I used BBEdit to write it. I did:
⌘N (“Link to New” ) to get a .txt file that Hook created and linked to the current Discourse topic.
It took a few tries to get this happening. The first couple of clicks on the licence key brought up a Buy dialogue box. The third try a couple of minutes later was successful. I don’t know whether your system takes a while to exchange purchase information between the relevant servers. If so, maybe a notice somewhere would soothe anxious customers?