We propose a semantic analysis of the particles afinal (European Portuguese) and alla fine (Italian) in terms of the notion of truth unpersistence, which combines both epistemic modality and constraints on discourse structure. We argue that the felicitous use of these modal particles requires that the truth of a proposition 𝑝∗ fail to persist through a temporal succession of epistemic states, where 𝑝∗ is incompatible with the proposition modified by afinal/alla fine, and that the interlocutors share knowledge of a previous epistemic attitude toward 𝑝∗. We analyze two main cases, that of plan-related propositions and that of propositions without plans. We also discuss the connections between truth unpersistence and evidentiality.