How to properly update Lion on Lion Server on Mac Mini Server 2011?

Question

macOS

Good afternoon dear community.
My question is the following, I bought a Mac mini Server 2011 and it so happened that for some time it was in use by another person who, having decided that he didn’t need the Server functions so much, demolished the Server and put the usual Lion to work . Everything would be fine, but it’s not clear how to get everything you need now, for example, for further sale (although I would tinker with the functions myself). Formally, I, being the owner of the server modification of the Mac mini, am the licensed owner of the OS server ruffles, but how to install them is not entirely clear. You can officially download the lion only from the Mac App Store. Hence the question - how to do it right? Maybe you should just download the image and put it on top (as far as I know Server comes as an appendage to the OS).

Answer 1

What is the problem with installing from the App Store (it should be available on the Purchases tab)?
Or from Recovery Mode?