One year after permanent residency has been finalized and you have once again sent a mere 7 days in Portugal in those 12 months, you are eligible to naturalize as a Portuguese national.

Once your Portuguese citizenship has been conferred, your passport is available by law and your unconditional residency options in respect to all the 27 Member states of the European Union become fully open to you.

Gaining a Portuguese passport is just like winning a Gold Medal in the Second Nationality Olympics!

source