To keep pig's blood for a month you need to keep it in the freezer of the refrigerator. Put the pig's blood into a plastic bag, then squeeze out the air in the bag, roll up the bag, tie it tightly with a rubber band, and then put it into the freezer of the refrigerator for preservation. Generally, pig's blood can be kept in the freezer for about a month, depending on the temperature and the quality of the blood. It is recommended to consume the preserved pig's blood as soon as possible so as not to affect the taste and quality.