I think that you could wear the ears, but you might want to put a patch or a pin on them that says something like Anniversary, or the # of years married. People there (guests & CM's) kept asking us when we were married, and if we were real newlyweds (only the guests asked this), so I guess they have a lot of experiences with people who aren't newlyweds wearing the ears to get the perks & recognition. I'd have felt bad lying to them about our wedding date, and it would have been weird to say, "Oh, we were married a year and a half ago" if we had taken our honeymoon much later, so you might want to add the patch or pin, to let people know it's for an anniversary, and that you're not newlyweds.
We saw a couple there with a 50 year anniversary patch on the ears, and it was really sweet (except the woman wouldn't wear hers!).
Also, it happened twice that other guests at a restaurant saw the ears and bought us drinks since we were newlyweds. If we hadn't really been newlyweds, I would have felt like we were taking their drinks on false pretences.
I see no problem with wearing the ears, but hopefully you can find some way to let people know that you're not actually newlyweds, to avoid confusion or having to lie to other guests or CM's.
Cheers!
Heather W