Article 31 defines the place of supply for telecommunication and electronic services, as specified in the Executive Regulation of the Decree-Law. The rule establishes that the supply location is determined by the extent of the actual use and enjoyment of the service. If a service is used and enjoyed within the State, the place of supply is considered to be in the State. Conversely, to the extent the service is used and enjoyed outside the State, the supply is located there. This 'use and enjoyment' principle explicitly overrides the location of the contract or payment when determining tax jurisdiction.