  In this perspective paper, we look into memory effects in out-of-equilibrium
systems. To be concrete, we exemplify memory effects with the paradigmatic case
of granular fluids, although extensions to other contexts such as molecular
fluids with non-linear drag are also considered. The focus is put on two
archetypal memory effects: the Kovacs and Mpemba effects. In brief, the first
is related to imperfectly reaching a steady state -- either equilibrium or
non-equilibrium, whereas the second is related to reaching a steady state
faster despite starting further. Connections to optimal control theory thus
naturally emerge and are briefly discussed
