terraform is OSS, unless you're using the hosted HCP version (workspaces? I think they're called), which, I've been using terraform heavily and at scale since v0.7 and I have never once thought I needed or would pay for something like that.
I'm well aware and have contributed to OpenTofu project in a small manner. I hope you'll forgive me slightly misspeaking - any version of terraform before that license change is OSS. It is, however, perfectly free to use and most companies I've worked with are hard-pinned on a particular version of terraform and rarely on the bleeding edge.
