Called M&M and rep checked with supervisor: my miles will not expire if I continue to have credit card activity every month. I asked what if they do expire Dec. 31st as account says, and they said to call to get them restored. They did not have a good answer why system shows that "xxxxxx award miles expire on 31.12.2018". Sounds like an IT glitch to me.

I had told the rep I had already sent in my question by email and had a ticket number, but that did not matter. She looked at my account by the usual verification. Still substantive response by email from M&M, so all this has to be handled by phone.