Originally Posted by
East_and_West
M&B award miles do not expire per se; only your M&B account will be cancelled if you haven't registered any flight activity for quite some time (5 years I believe?). As long as you keep crediting to M&B even a single flight mile during that period, your award miles from 10 years ago or even older will remain active and good to use.
Yeah, I haven't registered any flight activity in five years. I wonder if this expiry will be extended?