A drug delivery system comprises means to create a log of expelled dose amounts of drug. Stored dose amounts determined within a given time period are combined to a single combined dose amount. The given time period is initiated by a detected expelling event taking place (i) a given amount of time after a previous detected expelling event, or (ii) after a given detected action. By this arrangement it is possible to create a log corresponding to what a user considers to be a single dose, i.e. combining “split doses” to create a single log entry for a per se split dose.