1. A computer-implemented method of determining whether a user is allowed to access a content item, the method comprising: using a processor to execute steps comprising: receiving a query regarding whether the user is allowed to access the content item; determining, based on the query, a website associated with the content item; determining a set of offers associated with the website; determining, from the set of offers, a subset of offers that apply to the content item; identifying, from the subset of offers, an offer that includes a set of use-time rules specifying time periods during which the offer can be used to access content, wherein a use-time rule is associated with a user class; determining a class of the user with respect to the offer, wherein the user's class indicates at least one of: whether the user has accepted the offer and whether the user has registered with the website; determining whether the user is allowed to access the content item based on the offer, the user's class, and a current timestamp; and sending a query response that indicates whether the user is allowed to access the content item.