In Roman Catholicism, strict merit is is goodness bestowed on a person that is directly due to the person's work. An example would be a contractural agreement between two or more parties where a peron would get paid money for work performed.
Summary of positions: Condign merit (reward merit, not owed, but kindly given) the kind of goodness that is bestowed on a person because of the actions of that person. Congruent merit (merit from another) is the goodness bestowed on a person because of the work of another person. Strict merit (merit strickly due, as is a wage for work) is goodness bestowed as a contractural agreement between two or more parties.