Beginning October 1, 2018, PRH is moving from a perpetual access model (where libraries pay a higher price but retain access to the e-book forever) to a metered model (with lower prices on e-books that expire after two years). In a letter to library customers, PRH v-p Skip Dye said the change was made after listening to librarians’ feedback.
Source: Penguin Random House Changes Library E-book Lending Terms