It would appear that the AmEx Upgrade to Platinum 50,000 Membership Rewards Points (which is only available as a targeted offer) after $10K in spend over 5 months is NOT once in a lifetime but rather once per card account. In the past few months I have successfully 1. Upgraded a Biz Gold card to Biz Platinum performed the spend and received the bonus. 2. Downgraded a Biz Platinum to Green and then within less than 30 days received an offer to upgrade it [back] to a Biz Platinum for 50,000 more points after $10K spend. Both cards are in the exact same business name and I am the primary account holder for them both (they even share the same online login ID). Hope this helps. Now if they would just target me for the 2X points on $5,000 purchases the latest offer would net me a total of 70,000 points!