Does the client own the artwork when it is finished?
Yes. Once completed and paid in full, you, the client, own the artwork. That is exactly what a commissioned piece is. Upon completion, I may possibly use an image of your piece for "Portfolio Usage".
What does "Portfolio Usage" mean exactly?
It simply means that I would only use it as an example of my artwork on brochures and my Portfolio page here on this website. It WILL NOT be used to make prints, posters, etc...