I don't think Portugal has a motto, but according to this webpage:
http://www.azureva.co.uk/portugal/portugal-general-informations.html
it is "O bem da Nação" which means "The good of the nation".
I am Portuguese and have never heard this, so I still sustain it has no motto...
Portugal has no official motto.
From 1926 to 1974, the motto was 'Deus, Pátria e Família!' ('God, Country and Family'). On Apr 25 1974 the 'Cloves Revolution' took place and, since this was a fascist motto, it was basically forgotten and disused.
There is none. Not all countries have a national motto. Portugal is one such country. For it's not known to have a saying that either characterizes the entire nation or indicates the national mission. Portugal is located on the southwest coast of Europe. The country shares space with neighboring Spain on the Iberian Peninsula. And Spain has a national motto, which is 'Plus Ultra', or 'Further Beyond'. The motto is a challenge to the ancient warning that was carved into the ancient Pillars of Hercules. The Pillars were one of the seven wonders of the ancient world. They were located near the meeting of the Mediterranean Sea with the Atlantic Ocean. They served to warn ancient sailors of the limits of the known world of the Mediterranean. That warning was 'Nec Plus Ultra', or 'No further beyond [this point]'. But Portugal may not have found it necessary to have a national motto. It even may have been redundant to do so. For the Portuguese always have been known for going further beyond, in the challenges that they have raised and met. Examples are the founding of an independent nation, the keeping of a distinct national identify, and the knowing of the rest of the world through the courage and skills of their navigators and sailors.
The motto of Portuguese Empire is 'Vis Unita Maior Nunc et Semper'.
The motto of Kingdom of Portugal is 'The united force now and always'.
The motto of Kingdom of Portugal is 'Vis Unita Maior Nunc et Semper'.
The motto of Portuguese Army is 'Em perigos e guerras esforçados'.
University of Porto's motto is 'Virtus Unita Fortius Agit'.
The motto of Other World Kingdom is 'Women over men'.
Kingdom of Galicia's motto is 'Hoc hic misterium fidei firmiter profitemur'.
The motto of Kingdom of Hawaii is 'Ua Mau ke Ea o ka ʻĀina i ka Pono'.
The motto of Canada's Wonderland is 'Thrills Connect'.
The Kongo Kingdom traded with Portugal, when King Afonso was in power and after.
Kingdom of Portugal was created in 1139.
Kingdom of Portugal ended in 1910.
Portugal Cove-St. Philip's's motto is 'Where the Sun Meets the Sea'.
Kingdom of Redonda's motto is 'Floreat Redonda'.
Kingdom of Saxony's motto is 'Providentiae Memor'.
Kingdom of Holland's motto is 'Eendracht maakt macht'.
The motto of Kingdom of Romania is 'Nihil Sine Deo'.
The motto of Kingdom of Sarawak is 'Berharap Selagi Bernafas'.
Kingdom of Sarawak's motto is 'Dum Spiro Spero'.
Kingdom of Cochin's motto is 'Honor is our family treasure'.
The motto of National Republican Guard - Portugal - is 'Pela Lei e Pela Grei'.
Kingdom of Hungary's motto is 'Regnum Mariae Patrona Hungariae'.