Originally Posted by
tassojunior
M&M miles expire at the end of 36 months period even if there is account activity.
Holding the card is the only way to keep them from expiring so long as you make one purchase on the card every month. Miss a month and they're dead immediately.
Some people have contacted LH and gotten their expired miles re-instated if it was because of this glitch.
Plan to use the miles within 36 months !
And don't forget you'll be paying the annual fees each year, as you evaluate the merits of the program.