I have been visiting Norway for three months. Can I extend my stay?
No, an EU/EEA citizen can't apply to be in Norway for more than three months as a visitor or tourist. After three months you have to leave Norway.
Once you have left Norway, you can travel back to Norway immediately and start a new three-month stay as a visitor or tourist. There is no requirement for how long you should be outside Norway before you can come back.
When you are in Norway as a visitor or tourist, you are responsible for all your expenses during your stay here.
If you want to be in Norway for more than three months, you must exercise EU/EEA rights as an employee, self-employed person, service provider, student, have your own funds to support yourself or be a job seeker. Then you must also register according to the EU/EEA regulations.
If you have been in Norway for more than three months and do not exercise your EU/EEA rights, you can be notified by the police that you have to leave the country.