How long is the D3 visa valid and what do I do after arriving in Portugal?

Like Portugal's other residence visas, the D3 in your passport is valid for around four months and serves to get you into the country to complete the next step.

After arrival you attend an appointment with AIMA to obtain your residence permit, which authorises you to live and work in your highly qualified role long term. The permit is renewable provided you continue to meet the conditions, and the time accrued as a legal resident can count toward permanent residence and eventually citizenship.