This does look an interesting tool but I'm afraid isn't a great fit for this site, because although it is written in Go, there's no source available, so all I can see here is binaries in an empty repo with no information as to what has changed, so there's not much to interest those interested in the Go language. I'd definitely recommend working on the docs, and considering open-sourcing your tool, if you do please post it here again and I would upvote it. I don't think anyone's going to steal your idea or attempt to resell the binaries, so your main problem at this stage is just getting people interested and using your tools.
Open-source would be a good fit for this I think because you won't persuade normal end-users to download a binary from a website they haven't heard of or run it as a background task locally (most won't understand how), but you could sell a hosted version easily of the same tool, where you handle the hard bits (running the binary 24/7, sending out emails etc), and you could charge for that. I think a lot of people would be interested in paying for that sort of service (indeed many do already). People would probably be interested in being emailed the latest news for their keywords for example once a week (bit like google alerts).
IMO that would be a better model for you than trying to keep it closed source and generate interest when all you have to show are binaries. I hope this is helpful.