It is not always necessary to opt for an international medical insurance plan when you travel abroad.
Your choice will depend on the country you are moving to and what that country has to offer you in terms of medical coverage. Many countries have a local or a national medical plan which can be used when you are living in that country. Some countries require you to subscribe to a plan, in order to get your visa and other papers processed. When the country you are going to has a good national plan that not only has a good coverage, but is also priced nominally, you can opt for the local plan itself.