You must be doing something right if there is a mature student at the party, so first things first, congratulations. Your life is moving in the right direction. Mature students, as a rule, are somewhere else having way better parties than you can even imagine because they have reached a point in life where they have a way better idea of how to do them. If one of these elusive creatures can be found gracing the halls of your soiree (yes, we have those, and sometimes we even call them that) they will probably be in one of a handful of places.
They might be the one at the bar mixing cocktails because years of drinking experience has taught them there is so much more enjoyment to be gleaned from top shelf turps mixed to perfection than just smashing back a box of alcoholic sugar water in cans. They know the difference between good vodka and the Smirnoff you are swilling, and that any good spirit can be drunk on the rocks without drowning it in Coca-Cola. They will share this knowledge with you and help you refine your palate and your social graces if you show an interest and can spare a moment from puking your guts up in the bathtub.
They might also be found perusing the bookshelf because they know just how much that says about a person, and the endless shelves of Lee Childs, Maeve Binchy, David Baldacci and Jeffrey Archer are not impressing anyone. Or they could be thumbing through the record collection because they know what those are and how to play them. They will probably also know what is good and how decent mastering sounds as opposed to the mass-produced popular tripe with the gains maxxed out designed to deafen listeners. Dynamic range. It is a thing. These connoisseurs know this. If you see one of these types, know that they know something you do not.
Some of the more eloquent of these seasoned creatures will be holding court somewhere, surrounded by a gaggle of eager youngsters held in sway by stories of wild parties past. By the time one reaches a certain age they will have collected a bunch of stories that could make your hair curl. Things that will have to be seen to be believed. And you might not believe them, until one day when enough crazy shit has happened to you that you will understand truth is so often stranger than fiction. What back then seemed like a long yarn was probably a fairly regular Saturday.
Yet others may just be sitting quietly and observing. Humans are fascinating creatures and the drunken youth, when not obliterated beyond all reason like the ugly clichés they so often become, are amongst the most fascinating of all. The lack of the jaded cynicism of age is refreshing and beautiful. Keep your level head and you are a spectacle to behold. Enjoy it.