Software is a process.
It's never finished. There are always bugs to fix, features to add.
Usually, when one company buys another, they buy the software, not the process.
It would be more realistic to contract with a developer or group of developers the way book publishers contract with authors, or studios contract with directors. You buy N books, or movies, or albums. Then the creative person gives you what they contracted for.
Don't try to hire employees to make products. You need to be able to take creative risks. It's hard to do within a corporation. By "hard to do" I mean impossible.
Unlike movies, books, music -- software continually evolves. So even if the initial creator moves on, there always has to be the equivalent of a show runner that stays with the product, the kind of person who does what Vince Gilligan did on Breaking Bad, for example.
I've now moved on from two products, one through acquisition and one by passing off to a new management team. Both times the product died.
I'm still trying to figure this out.