The invention concerns a process to protect a vulnerable software working on a data processing system against its unauthorized usage using a processing and memorizing unit. The process comprises defining: 1) at least one software execution characteristic, liable to be monitored at least in part in a processing and memorizing unit 2) at least one criterion to abide by for at least one software execution characteristic 3) detection means to implement in a processing and memorizing unit and enabling to detect that at least one software execution characteristic does not abide by at least one associated criterion 4) coercion means to implement in a processing and memorizing unit and enabling to inform the data processing system and/or modify the execution of a software when at least one criterion is not abided by.