Planet atmospheric escape induced by high-energy stellar irradiation is a key phenomenon shaping the structure and evolution of planetary atmospheres . Therefore , the present-day properties of a planetary atmosphere are intimately connected with the amount of stellar flux received by a planet during its lifetime , thus with the evolutionary path of its host star . Using a recently developed analytic approximation based on hydrodynamic simulations for atmospheric escape rates , we track within a Bayesian framework the evolution of a planet as a function of stellar flux evolution history , constrained by the measured planetary radius , with the other system parameters as priors . We find that the ideal objects for this type of study are close-in sub-Neptune-like planets , as they are highly affected by atmospheric escape , and yet retain a significant fraction of their primordial hydrogen-dominated atmospheres . Furthermore , we apply this analysis to the HD3167 and K2-32 planetary systems . For HD3167 , we find that the most probable irradiation level at 150 Myr was between 40 and 130 times solar , corresponding to a rotation period of 1.78 ^ { +2.69 } _ { -1.23 } days . For K2-32 , we find a surprisingly low irradiation level ranging between half and four times solar at 150 Myr . Finally , we show that for multi-planet systems , our framework enables one to constrain poorly known properties of individual planets .