All Montana residents above the age of 11 must obtain a hunting license. The same applies to non-residents. Resident and non-resident youth hunters (12 to 17 years) are eligible for the youth hunting license which is cheaper than the regular hunting license.
The state of Montana has special licenses for seniors, people with disabilities, youth and military/veterans.
It is always easier to apply for your license via the official website. Alternatively, see if there is a vendor in your neighborhood.