Some school bookstores sell prepaid access keys to students, to allow students to directly use financial aid. Note: Most students on financial aid subscribe via credit card at zyBooks.com, which may have a lower price, enable future discounts/refunds, and save time. See this article on financial aid. (A few schools include the subscription cost in the student's fees, so provide access keys to all students).
A zyBook prepaid access key is 10 characters and starts with zy, like zy123abc45 (just an example).
To use an access key, students first go to a zyBook's home page. If unsubscribed, a price will appear, followed by a payment info area. That area may have an access key box:
Upon entering a valid access key, the price will drop -- usually to $0, so no credit card is needed.
Once the key is applied, click the orange "Subscribe" button to finish the process.
An access key is specific to a particular zyBook code, and cannot be used for a different zyBook code (including for a different term).
NOTE: The access key box only appears if that particular zyBook code has access keys issued.
Sometimes the item provided by the bookstore has the zyBook prepaid access key in hard-to-find spots (like another paper stapled to a receipt, or on their website that students must log in to).
If your access key does not work, or no access key box appears, your bookstore may have provided a wrong key (different class, previous term, etc). Contact firstname.lastname@example.org with info (zyBook code, access key, instructor/class name, etc.) and we'll try to get you learning ASAP.