Just received invite for the Presidential Plus card.

It mentions Flex EQMs, and the Presidential Plus Card mentions that and other benefits.

What is a "Flex" EQM?

Can I keep it from year-to-year, and just apply it when I'm short of EQMs to qualify for Platinum, Gold or Silver?

Do the earned Flex EQMs disappear if you don't renew the Presidential Plus Card?

While I'm in geat shape this year (EWR-SIN) and possibly another before year end, and Melbourne last year, in 2005 I kept Platinum only by taking a week in Rio (From EWR via IAH), to squeeze out what was needed.

Would be great to have a bit of insurance in hand, just in case.