[tzs]

The first thing to do is figure out if they have the legal right to sell it. If it was developed by a contractor the odds are very high that it is not a "work for hire" and the contractor owns the copyright, unless there was a copyright assignment in the contract. Saying in the contract that it is a work for hire is not sufficient.

(I am assuming this was in the US)

Google "computer software and work for hire" for more info. Sorry for giving no links, but I'm tapping this out on my iPhone while waiting for a take out pizza to become ready.