Fumoto valves can easily outlast the life of your vehicle. Many customers even remove their valves from a vehicle they're selling and install it in a new vehicle if the sizes are the same.
As for the gaskets or o-ring, you don't need to replace them in most cases. However, if you remove the valve and install it again into the oil pan, please replace the gasket or o-ring. In case oil leaks from the gasket, you may need to replace the gasket or o-ring to fix the issue.
You can always purchase a few extra gaskets, just in case.