I would not eat tamales after being refrigerated for more than 1 week. We have frozen tamales and had them frozen for close to 9 months. After removing from freezer, we steamed the tamales and they were just fine. We always purchase quite a few dozen around the holidays, freeze what we don't need right away. That way, we always have some on hand.
You could refrigerate tamales as long as you want , nothing will happen to them if you leave it a long time. My mom usually refrigerates tamales for a long time and when she gets them out they still taste the same.