Bye law 517/2008 that regulates Decree law 39/2008 regarding temporary accommodation establishments - `´summer lettings´` was finally published in June 2008 comes into immediate effect.
This is a legal requirement in plain english if the following is not adhered to your home and finances are at risk.
In order to open doors to the public and start working providing temporary accommodation ,one has to follow certain steps and requirements:

Produce a valid habitation permit issued by the camera ( local government office )
Make a written request to the president of the camera according to the format published by bylaw 39/2008 March
Provide proof of ownership
supply current safety certificates by qualified Portuguese technicians
A floor plan of the building showing apartment or apartments intended to be licensed.
The apartment should be of reasonable quality inside and out.All equipment installed in the property should be in good working order.
The caderneta (deeds registered with the land registry )
After submission of the above documents to the camera you may then legally let the property and the camera will carry out their own inspection within 60 days.

Safety regulations
Regulations required vary on type of establishment,as an example for a 1 bedroom apartment equipment required as follows:-
ABC Fire extinguisher
Fire Blanket
Smoke alarms
Carbon Monoxide Detector
Gas detector ( query if required )
Information regarding emergency services and general information
Complaints book/Portuguese / Livro De Reclamacoes

In plain english under the above  bye law it is illegal for any person to rent any property intended for holiday let or short term rental in Portugal that does not comply with the current regulations and does not have AL ( Local De Aljamento ) This is not a requirement but a legal obligation of the owner or letter of any holiday apartment or villa.
There are different regulations regarding long term rentals,however this still requires registration with the local finanaces department.

Whilst the above is  general the system in Portugal is liable to change at short notice and there may be further requirements.