I emailed the company that made it and they said that they don't know what software it would go with because they sell blank dongles to developers that program them themselves.
I'm guessing this thing is useless to anyone, except maybe whoever owned it originally. And, as such, I think I am more than happy to pry it open and see what's inside!
:banana:
Incidentally, a google search for "sentinelpro dongle amiga" has this thread as the first hit. Everything else goes to stuff about hacking and making fakey software dongle emulators and such.