1. A computer-implemented method comprising: applying, using a processor, a tag to a content item owned by a first entity, the tag including at least a unique identifier associated with the content item; determining that a web page associated with a second entity uses the content item for display on the web page, wherein the second entity is different from the first entity; using the tag, identifying a sharing level associated with the content item, the sharing level indicating permitted use of the content item by an entity; determining a permission status of the use of the content item on the web page of the second entity based on the sharing level associated with the content item, the permission status being one of permitted use and not permitted use; determining a plurality of cost-per-use amounts for the content item based on the sharing level and characteristics of an entity using the content item; and adjusting at least one of the plurality of cost-per-use amounts for the content item based on a correlation between a click-through rate of an advertisement and the advertisement being displayed on a web page with the content item.