1.cs

namespace Fohjin.DDD.Domain.Client
{
    public class Client : BaseAggregateRoot<IDomainEvent>, IOrginator
    {
        private Address _address;

        public Client()
        {
            registerEvents();
        }

        public void ClientMoved(Address newAddress)
        {
            Apply(new ClientMovedEvent(newAddress.Street, newAddress.StreetNumber, newAddress.PostalCode, newAddress.City));
        }

        IMemento IOrginator.CreateMemento()
        {
            return new ClientMemento(Id, Version, _address.Street, _address.StreetNumber, _address.PostalCode, _address.City);
        }

        void IOrginator.SetMemento(IMemento memento)
        {
            var clientMemento = (ClientMemento) memento;
            Id = clientMemento.Id;
            Version = clientMemento.Version;
            _address = new Address(clientMemento.Street, clientMemento.StreetNumber, clientMemento.PostalCode, clientMemento.City);
        }

        private void registerEvents()
        {
            RegisterEvent<ClientMovedEvent>(onNewClientMoved);
        }

        private void onNewClientMoved(ClientMovedEvent clientMovedEvent)
        {
            _address = new Address(clientMovedEvent.Street, clientMovedEvent.StreetNumber, clientMovedEvent.PostalCode, clientMovedEvent.City);
        }
    }
}

2.cs

namespace Fohjin.DDD.Domain.Client
{
    public class Client
    {
        protected virtual void Apply(object @event) { }
        protected IEnumerable<Type> RegisteredEvents()
        {
            yield return typeof(ClientMovedEvent);
        }

        protected virtual Address Address { get; set; }

        public void ClientMoved(Address newAddress)
        {
            Apply(new ClientMovedEvent(newAddress));
        }
    }
}