Ask HN: How are enterprise web apps distributed?

Hey,

I have built a web application for a company and initially I wanted to host it on my servers and provide them access via a login and password. The company is insisting that the software and its data must live on their servers.

The web application is coded in Django with Postgres as the database. How do I distribute the application on their server without giving away the source code?

And in general, how are enterprise applications distributed? And how are updates provided?

Thanks!