> Ownership of property is a Natural Right. Property includes intangible entities such as software.
Ownership of a good consists of the right to consume it, to use it up. As such, ownership only comes into play when someone else consumes your property. The exclusivity of this right is merely a side-effect of scarcity: two people cannot both consume the same scarce good. Intangibles are not scarce and cannot be consumed, ergo ownership does not apply.
The rights to restitution and retribution which permit the enforcement of natural property rights are justified only on the basis that they are a response in kind to damage caused to your own property. This is why property is called a natural right: one cannot usurp anothers' property rights without providing the justification for a response in kind. There is no justification for seeking restitution or retribution simply because someone /benefited/ from your work while causing no harm to you.