If a company disappears, their software doesn't suddenly float around without an owner. What usually happens is that there is an auction of assets (often for a fraction of their previous value) which includes intellectual property. Sometimes the result can be that one person owns the name, while another owns the product rights. Sometimes they can go through a pre-packaged buy-out, which almost inevitably means the previous owners buying out their own company, minus debts, staff pension fund responsibilities, and property rental contracts which they would otherwise have had to pay off. Hey presto, Daves-Magic-PCB-Co(2001) Ltd becomes Daves-Magic-PCB-Co(2011) Ltd, with little debt, no big financial responsibilities, and they lost all the expensive staff overheads.