This is a very standard thing to (a) do, and (b) be demanded in a contract.
It's not zero effort, but it's not that hard. There's plenty of firms provide the service.
Every time my former company shipped a release, we'd bundle up the source code, libraries, build scripts, etc, burn a DVD and send it off to Iron Mountain. Every time you do a sale that wants escrow, you add their details to the list and send that off to Iron Mountain too.
These days, I'd probably ship a Docker or VM image from the CI system: you need to give the customers something they can use to create their own builds.
We had some customers who actually tested the process, and when the company was sold and the product canceled, one customer took the option of getting the source code, and continued to make their own builds for a bunch of years afterwards.
It's not zero effort, but it's not that hard. There's plenty of firms provide the service.
Every time my former company shipped a release, we'd bundle up the source code, libraries, build scripts, etc, burn a DVD and send it off to Iron Mountain. Every time you do a sale that wants escrow, you add their details to the list and send that off to Iron Mountain too.
These days, I'd probably ship a Docker or VM image from the CI system: you need to give the customers something they can use to create their own builds.
We had some customers who actually tested the process, and when the company was sold and the product canceled, one customer took the option of getting the source code, and continued to make their own builds for a bunch of years afterwards.