You can protect your invention in other countries by claiming priority for a Monegasque patent (within one year of filing) and opting for one of the following three extensions:
National extension, by filing a patent application directly with the intellectual property office in the country concerned.
European extension, by filing a European patent application with a receiving office or the European Patent Office (EPO).
International extension (PCT system), by filing an international patent application with a receiving office or the World Intellectual Property Organization (WIPO) for your selected countries. You do not need to hold a Monegasque patent application or a full patent to choose this route (direct PCT route).