last hurrah

A final act, achievement, or effort. Finishing the month-long project was Cheri's last hurrah before she left the company to pursue another opportunity.

A final appearance, especially at the end of one's career. The phrase has a bittersweet, if not sad, connotation, since it's applied to the end of a person's life's work. It could refer to a musical or theatrical performance or the end of a political career—the final time that the person will hear an audience or crowd shouting in praise. Swan song has a similar meaning, although not always used in a positive sense.