In my cynical view, herder now seems to be an attempt to commercialize tmux by adding superficial polish. I am wary of VC backed developer tools that seek to innovate in well established open source niches. Herdr by default is mouse focused, has very friendly UI interactions, and has some niche UI support for agents running in panes. Great. Now it also has a profit motive and ROI pressures. I don't see this ending well.

If he wants to make money he needs to sell licenses, not give them away for free. To that end, making the free version AGPL is generally a good move. It ensures people can get hooked on your product and when they start working at corporations they have to pay to keep using it.