This is pretty standard for dealing with enterprise clients. They literally just want a copy of your code in escrow so they're not left hanging if you go out of

This is pretty standard for dealing with enterprise clients. They literally just want a copy of your code in escrow so they're not left hanging if you go out of business. They usually pay the escrow costs and you ship a CD-ROM or something. In my experience, this just happens once and nobody thinks to ask for updates once it's done.