When you live in the Netherlands, you are in most cases compulsorily insured for a basic package that covers essential healthcare. After leaving the country, this insurance will usually end. You will need to find a proper health insurance in your new country of residence. Your payments to the insurance company in the Netherlands will stop on the day you leave the country, provided you have notified the insurance company in time.
If you need some overlap until you are settled in your new country of residence, it might be best to take up travel insurance for the time being.