Can a researcher in Finland eventually apply for permanent residence?

Researchers who hold a continuous (A) permit accumulate continuous residence that can count toward a permanent residence permit.

The general requirement is a continuous period in Finland on an A permit, around four years, though additional conditions such as income, work history, education or language skills may apply under the rules in force when you apply.

If long-term settlement is your goal, keep your residence continuous, avoid long unbroken absences, and track your qualifying period so you can apply for the permanent permit once you meet the conditions.