Generalized Langevin Equations are an exact description of the motion of an observable deriving from the projection of the full manybody system dynamics onto a single (or a few) selected degrees of freedom of the system. The prediction and interpretation of the memory function, containing the non-Markovian character of the observable, is however not fully understood or often elaborated using approximations. Here, we will show how to extract and parametrize GLEs from molecular dynamics simulations and how this can bring a novel analysis tool to investigate molecular processes.