End grain cutting boards, when properly cared for, will last for generations. Simply wash with soap and water and stand up to dry. Always rinse off both sides of the board whenever washing and NEVER let it stand it water, soak in a sink, or place in a dishwasher.
If your cutting board is ever looking dry just wipe it down with walnut oil from a natural food store or mineral oil. There are serveral commercial wax based products you can use as well.
Part of the beauty of any cutting board is the marks it acquires over time, showing it’s individual history. If you ever want to refinish it to look like new it can be sanded down and re-oiled. Just be aware end grain does not sand easily!