What are the requirements for an EU citizen to obtain a registration certificate in Portugal?

For an EU citizen to be eligible for obtaining a registration certificate in Portugal, he or she must at least meet one of the following requirements:

• A valid passport
  
• Proof of employment or self-employment, or having enough funds for you and your family to live in Portugal

Subscribing to health insurance in Portugal (if the same applies to Portuguese citizens in your country of origin).