Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Alojamento Local (AL) Restrictions
If you plan to buy property to rent out to tourists (Airbnb style), be aware that new AL licenses are currently suspended in high-density areas like Lisbon, Porto, and parts of the Algarve under the "Mais Habitação" law.
Condominiums (building assemblies) now also have the power to ban short-term rentals in their buildings with a simple majority vote. Always check the specific regulations of the municipality and the building before investing.