The topic of «agreement-related fees» is very little investigated in legal doctrine. An agreement signed by Fim-Cisl, and not by Fiom-Cgil, in a Venetian metal-engineering company (Pometon S.p.a.) provides that non-unionised workers and workers members of the non-signatory union are given the possibility to individually subscribe to it by paying the equivalent of a yearly union fee. The agreement raises several issues and questions multiple aspects of the theoretical framework of union representativeness and of the subjective effectiveness of company-based agreements. The essay aims at analysing and reconstructing what actually happens in the metal-engineering sector, where union cohesion has long been abandoned.