The attorney general or a district or county attorney on the attorney's own initiative may, or in response to a complaint shall, investigate violations of this subchapter. If the attorney believes that a violation has occurred, the attorney may sue in the name of the state for an injunction against a person who:
(1) is violating a provision of a marketing agreement, a license, or an order or rule of the department to which the person is subject; or
(2) engages in transactions mentioned in and regulated by a license during suspension or after revocation of the person's license.