Farm profitability and efficiency are essential factors for sustainable dairy production. Previous studies indicate that dairy producers often underestimate the cumulative costs and preferentially consider current events for making decisions especially in keeping cows in the herd. The objective of this study was to investigate the main criteria used by producers for a cow to stay in the herd for an additional lactation. Data originated from production and health records from Valacta DHI and herd health files for cows up to the fourth lactation and born between February 1997 and March 2012 across 114 herds in Quebec, Canada. The data set included production costs (feed costs, costs of health events) and revenues (milk value, margin over all costs), accumulated on lactation (LAC) and productive lifetime (PLT) basis. A cohort of cows in a herd that stayed in production for an additional lactation (ST) was compared with a cohort that left by the end of lactation (LF) through paired t-test analyses. LAC costs of health events were higher (P < 0.01) for the LF than ST cohort in each lactation, in particular as of lactation 3. LAC feed costs were higher (P < 0.05) for the LF cohort only in lactation 1–2. LAC revenues were considerably lower for the LF cohort, in particular for margin over all costs (P < 0.01). These results suggest that revenues generated at the current lactation largely influenced the stayability in the herd. Profitable cows appeared to be more feed-efficient until lactation 2, and less likely to encounter diseases at later lactations. PLT costs progressively increased at a larger rate (P < 0.01) for the LF cohort, in particular for feed costs. Yet, PLT milk value was higher (P < 0.05) for the LF cohort, whereas PLT margin over all costs did not differ (P > 0.1) between cohorts. These results suggest that cows that are more profitable could be retained in the herd if cumulative costs over a lifetime are considered. Lifetime cost-benefit assessment has the potential to inform producers on keeping the most profitable instead of the most yielding cow in making a decision to retain an animal in the herd. This is a powerful tool to improve herd profitability and longevity.