Originally Posted by lokijuh

Redeemed miles retain their original expiry date. Also they don't get picked up in extensions, so they automatically expire when returning to the account (if their original expiry date had passed), although if they were due for extension you can appeal this.

So, to illustrate. You have miles expiring in June 2022, which you use in May for an award ticket in say April 2023. You decide to cancel in November, they return to your account, and they expire automatically. But as miles would have been extended to December 2022, you can appeal that and they should be reinstated. Or if you decide to cancel in March, the miles would have been extended to December and then again to June 2023, so again you would have to appeal the expiry.