Just checked my account. I took a flight the end of June but it was a reward flight purchased with some other tickets on May 31, the last day for the May Promo. Under my miles it says they all expire May 31, 2025. So it's 2 years from any mileage activity (out in my case) and the June 30 flight does not count since it produced no mileage and was redeemed May 31 2023.