You can protect your trademark in other countries by claiming priority for a Monegasque application (within six months of filing) and opting for one of the following two methods:
National route, by filing a trademark application directly with the relevant office in the country concerned (some national offices offer an online filing service). In some cases, it is mandatory to be represented by an accredited IP agent.
International route (Madrid System), by filing an international trademark application based on a Monegasque trademark with the World Intellectual Property Organization (WIPO) - via the Monegasque Industrial Property Division acting as the Office of Origin. You will need to show a connection with the territory of the Principality of Monaco (nationality or residence for natural persons, effective and earnest place of business for legal entities).