I think this analogy is even better than I first thought. Many companies (mine included) not only pay for their own expenses, but for entertainment and pleasure for their employees. My company takes us out several times a year for parties, cruises, lunch, etc. They pick up the bill, but we have to sign for it (accept it). No, we can't use it to buy personal items (groceries, etc), only things that they want us to have.
This is much like the way Jesus paid for our sins. He did not pay for them so we could just live our lives the way we want to free of consequences (buying personal items), but so we could be released from our sin and enjoy the blessings He wants for us (treating us to parties, etc). He is paying in full, but on His terms. All we have to do is accept it.