Accounting for online system user actions occurring greater than a reasonable amount of time after presenting content to the users when selecting content for users

A computer program product comprising a computer readable storage medium having instructions encoded thereon that, when executed by a processor, cause the processor to:

• receive content items at an online system for presentation to users of the online system;
• maintain information describing presentation of one or more content items to users of the online system at the online system;
• receive information from a third party system associated with a content item describing actions performed by users, the information including information identifying one or more performed actions, values of the one or more performed actions to the third party system, and information identifying users who performed the one or more actions;
• identify users of the online system corresponding to the information identifying users who performed the actions;
• determine information describing presentation of the content item to the identified users;
• generate a model predicting a value to the third party system of presenting the content item based on the information describing presentation of the content item to the identified users and the received values of the one or more performed actions;
• identify an opportunity to present content to a viewing user of the online system;
• and
• include the content item in association with a characteristic of the content item determined based on the model in one or more selection processes selecting the content for presentation to the viewing user.