A spouted pouch comprising: - a flexible material pouch body, - a spout having a spout body with at a lower end thereof an attachment portion that is attached to the pouch body, wherein said spout body has at an upper end thereof a tubular neck, which neck has an interior surface delimiting at least a section of a product passage that extends from a lower product passage opening through the spout body to an upper opening at a top end of the neck, said neck having an exterior surface provided with a first screw thread, wherein the spout body is provided with a rotation preventing boss (25,26) at a location outward of the neck and below said first screw thread, - a closure device that is secured on said neck of the spout, wherein said closure device comprises: - a socket configured to the screwed onto the neck of the spout, - a user openable or user removable cap supported on the socket in a manner so as to be openable or removable relative to the socket, wherein the socket comprises a molded socket body of plastic material having a bore extending through the socket body from a lower end of the socket to a discharge opening at a top end of the socket, wherein the bore is configured to receive at least a portion of the neck of the spout therein, and wherein the bore has an interior surface provided with a second screw thread that is configured to cooperate with the first screw thread upon screwing the socket onto the neck of the spout, wherein the socket body has an exterior surface of which at least an upper section defines a discharge portion having said discharge opening, wherein the cap, in a closed position thereof, covers the discharge portion, wherein the socket body is provided at the lower end thereof with a permanent snap lock anti-back off structure comprising at least one permanent snap lock anti-back off portion (61,62) characterized in that the at least one permanent snap lock anti-back off portion (61,62) is configured to flex over the rotation preventing boss (25,26) upon screwing of the socket onto the neck of the spout and then snap behind said rotation preventing boss, wherein said permanent snap lock anti-back off structure is configured to remain intact upon a user opening or removing the cap for the first time, and in that the closure device is a hinged cap closure device, wherein the cap is a hinged cap, that is hinged to the socket, for example wherein the socket and the hinged cap are integrally molded from plastic material with an intermediate hinge, e.g. a living hinge, between the socket and the hinged cap. - a flexible material pouch body, - a spout having a spout body with at a lower end thereof an attachment portion that is attached to the pouch body, wherein said spout body has at an upper end thereof a tubular neck, which neck has an interior surface delimiting at least a section of a product passage that extends from a lower product passage opening through the spout body to an upper opening at a top end of the neck, said neck having an exterior surface provided with a first screw thread, wherein the spout body is provided with a rotation preventing boss (25,26) at a location outward of the neck and below said first screw thread, - a closure device that is secured on said neck of the spout, wherein said closure device comprises: - a socket configured to the screwed onto the neck of the spout, - a user openable or user removable cap supported on the socket in a manner so as to be openable or removable relative to the socket, - a socket configured to the screwed onto the neck of the spout, - a user openable or user removable cap supported on the socket in a manner so as to be openable or removable relative to the socket, wherein the socket comprises a molded socket body of plastic material having a bore extending through the socket body from a lower end of the socket to a discharge opening at a top end of the socket, wherein the bore is configured to receive at least a portion of the neck of the spout therein, and wherein the bore has an interior surface provided with a second screw thread that is configured to cooperate with the first screw thread upon screwing the socket onto the neck of the spout, wherein the socket body has an exterior surface of which at least an upper section defines a discharge portion having said discharge opening, wherein the cap, in a closed position thereof, covers the discharge portion, wherein the socket body is provided at the lower end thereof with a permanent snap lock anti-back off structure comprising at least one permanent snap lock anti-back off portion (61,62) characterized in that the at least one permanent snap lock anti-back off portion (61,62) is configured to flex over the rotation preventing boss (25,26) upon screwing of the socket onto the neck of the spout and then snap behind said rotation preventing boss, wherein said permanent snap lock anti-back off structure is configured to remain intact upon a user opening or removing the cap for the first time, and in that the closure device is a hinged cap closure device, wherein the cap is a hinged cap, that is hinged to the socket, for example wherein the socket and the hinged cap are integrally molded from plastic material with an intermediate hinge, e.g. a living hinge, between the socket and the hinged cap.