The relationship between metacognition and memory in aging is complex, with older adults often expressing memory concerns yet sometimes displaying overconfidence in prospective memory (PM) tasks. This study examined how metacognitive judgments of PM performance are influenced by the reference point used (self vs. peers), the timing of metamemory assessments (before vs. after PM task), and subjective age. In two preregistered online experiments, younger and older adults completed an event-based PM task embedded in a lexical-decision ongoing task. Metacognitive assessments included pre-task performance predictions and memory-related questionnaires. In Experiment 1, we manipulated the reference point used to evaluate performance and the order of administration of the PM task and the metamemory questionnaires. In Experiment 2, we refined the peer comparison, added a control condition, assessed both prospective and retrospective metacognitive judgments, and explored how subjective age influenced these judgments. Across both experiments, participants were overconfident when comparing themselves to peers, but underconfident when making general performance predictions; retrospective judgments were better calibrated. Although older adults performed similarly to younger adults, they reported better self-perceived memory, regardless of actual performance. Subjective age was positively associated with overconfidence in older adults. Finally, completing the PM task before metamemory questionnaires led to lower self-ratings and more reported memory failures across age groups. Overall, these findings underscore the reactive effects of metacognition to different reference points and the order of instrument administration, highlighting the role of external comparisons and procedural factors in shaping how individuals perceive and evaluate their memory abilities.