That's right, the code was not open source, it was shareware. In those days, I either wasn't aware, or there weren't widely available and understood licenses y

That's right, the code was not open source, it was shareware. In those days, I either wasn't aware, or there weren't widely available and understood licenses you could use. I agree that this was a scary consequence of making my software available. I paid a lot more attention to licensing after that experience, and I now use standard open source licenses to protect myself as well as the work.