Oh for the love of tech, do chase them. This absolutely has to be in void of the terms of your trial take them to court. If not, then at the very least name and shame the company, so some dumb manager orchestrating this silly theft will get fired and someone more mature can be rotated in.
We’re not rushing into legal action — it’s not worth the energy for now — but publicly calling out the behavior felt necessary. It also sends a message to others in the ecosystem about the kind of nonsense OSS maintainers sometimes face.
And yes, while I’m still holding off on naming the company directly… I haven’t ruled it out.
When I was a teenager I would do super cut-rate work on computers for people, and my father did helpfully point out that undercharging for valuable work just makes it harder for people whose day job is to do the same work, because then they have to compete with a naive teenager. You're the kind hearted OSS / freemium vendor in this case. Threatening legal action costs nothing. Punishment is meant as a deterrent for antisocial behavior. Failing to even threaten them will result in less money going to people who deliver a public good.
You say that as if that is some bad thing. As a vendor you want to have a reputation for asking what you are fairly owed. The other option is to have a reputation for being a wet tissue anyone can walk through.
> You don't threaten legal action against companies before calmly advising them of the situation.
These are not incompatible with each other. Of course you calmly advise the company of the situation. 100%. You tell them that their 15 day trial period lapsed at <date> and that they continue using the <product> without proper license in place. You tell them where they can reach out to find the right licence for their needs. And you tell them that you intend to pursue them for damages if they remain out of compliance. All very calmly and professionally. Nobody is angry with anyone here. There is no bad blood. It is just a contracting oopsie!