copying text from Digital Editions

Hi I can no longer copy text from the digital edition of the textbook that I´m teaching. The publisher says that there´s a limit of 15 pages per year. However, I haven´t come near that. I don´t even think I copied sentences 15 times. It´s very useful to copy to a PowerPoint so that I can highlight and arrange the text to make it easier for the students to understand. What can I do so that I can copy again? Thanks.