To be quite honest, I've never tried to freeze a cooked eisbein. I would imagine that once defrosted the skin would lose its crispness and become rubbery and unappealing. However, if you are planning on using the leftover meat in another recipe, this can be cut into cubes and frozen in a freezer bag or air-tight container for up to 3 months. Let the meat defrost in the refrigerator before using it in your recipe.