Be sure to purchase either the 24 month from Pearson via Canvas or from the campus bookstore.
To avoid any issues, purchase full access before the trial ends. This is particularly problematic for students outside the US. Important Note: Allowing the temporary access to expire before making the purchase or entering a purchased access code has been known to corrupt student accounts.
It is typically needed when your textbook/access card doesn't arrive before the term begins. There is a 14-day Temporary Access available during the first two weeks of the term. Temporary Access to Assignments & Digital Textbook
You can purchase access to MyLab and Mastering as well as the Pearson textbook using a few methods