Copyright can, and often does, belong to a company. If nobody buys the intellectual property of a company that goes out of business, then it would be unlikely there would be any civil repercussions for pirating the software (if it was being sold there could be criminal charges). There is probably some kind of expiry date on copyright, but I don't know how long that is. I know for books copyright remains with the author, and then their estate, for something like 100 years after their death. Software would be less than this, but probably long enough the program would be pretty much useless by the time the copyright was up.
