A plug counter includes a seat receptive of a plug in a first position and capable of passing the plug in a second position. A first sleeve is in operable communication with the seat and is longitudinally movable in response to movement of the seat between the first position and the second position. A second sleeve is in operable communication with at least one of the first sleeve and the seat and is configured to index upon passage of the plug. A key is in operable communication with the seat and is configured to prevent movement of the seat to the second position after a selected number of plugs have passed the seat. A third sleeve is in operable communication with the first sleeve, and a release member is in operable communication with the third sleeve and is configured to move the third sleeve after it is released.