I believe I have read that you could go to an SPG hotel and order something to eat from the restaurant that would add activity to extend your miles. You would need to give them your SPG number. Get an SPG membership card you could show them. That is what I plan to do. I just canceled our SPG Amex cards from a year ago.

My points are good through July next year. So it looks like it requires an addition every 12 months to keep them active.