If you don't have a driver's license issued in Montenegro, then it's likely you'll need to get an International Driving Permit (IDP) in your place of residence to be allowed to rent a car. Please also consider that if an IDP is required, it won't be valid on its own. You'll have to show your current driver's license your passport and other forms of identification as well. Lastly, make sure the credit card you used to book the rental matches the name on your driver's license and passport. A few other things to note to rent a car internationally are:

• Age restrictions: You need to be at least 25 in many countries to rent a car. If you're younger than that, it may still be possible to rent a car but you'll have to pay a Young Driver's Surcharge. Additional restrictions may also apply to the types of vehicles you can rent.
• Driving limitations: Be sure to read the rules and regulations before sliding behind the wheel. You typically can't cross country borders, drive on ferries or on off-road areas with a rental vehicle.