"We are time's subjects" notes Hastings as the rebels make preparations for another insurgency against the king (1.3.8). This is a sharp reminder that even in the midst of civil rebellion and chaos, there's one certainty – everyone is "subject" to the passing of time. In Henry IV Part 2, the spirited and larger than life Falstaff is aging and Henry IV is at death's door as the play anticipates the moment when Prince Hal will be crowned King Henry V. While characters in the play look forward to the future, they are also hyper-aware of the past. Memory plays a prominent role here and the play is deeply interested in the way we interpret (or misinterpret) our pasts and how our understanding of history can shape future events. While some (like Shallow and Justice) look on the past with fondness, others recall bygone events in an attempt to explain present circumstances, to imagine what the future might be like or, to speculate about how things might have been if only the past were different.
When Hastings's notes that "[w]e are time's subjects" (1.3.8), he articulates one of the play's most important concepts – everyone (including the monarch and the rebels who resist the king's authority) is powerless against the passage of time.
Henry IV Part 2 is a nostalgic play that regards the past with both fondness and regret, even as it looks hopefully toward the future.