How many of us, or how many times we upgrade them? I guess the first one. I upgrade only part of my Moonstone Library, to save "restoraticles" (Royal Restoration thingies). When it will become obsolete, I intend to dismantle it and then repeat the process of building it. But, if in the future I manage to get better flow of won "restoraticles", I will definitely upgrade the rest, and keep the thing! If it would still be of any worth at that stage.