Well, in The Hitchhiker's Guide to the Galaxy, the ships pretty much ran themselves - which was convenient because they were usually crewed by morons (better for his style of comedy).
But let's assume it's not that easy.
Here in the real world, there are two fundamental approaches to making something work long term.
One is to overengineer it so much that it is zero maintenance.
The other is to make it require frequent - but straightforward - maintenance.