This Trophy comes from Natural Progression
Once in the velvet room, speak to Margaret. In the list of things she offers you can register any Persona's you obtain and buy any you may not have any more due to releasing them or fusing them with others. When you register a Persona you register it as it is, with all the abilities it currently has ect. You may then buy back Persona's (to help with social link increases or fusions) for a cost. Simply buy any persona from the Compendium and the Trophy is yours! The price differs slightly, so the higher the level Persona the more it will cost.