Presumably, like most other small companies, if they went out of business they would find a way to open the software up. There are several products where when the company went out of business or discontinued the product, they'd either post a permanent key or let you download an unlock or something.
While I'm not a supporter of DRM, it's not anywhere near as invasive or annoying as most models of DRM are. Ideally, it would be unnecessary, but they don't have the time to go around voiding every CD key that winds up on the Interwebs.
Makes sense.