This article reports on the analysis of COUNTER-compliant usage data of Elsevier Science Direct journals for the period of 2004-2009 by Consiran, an Iranian national consortium with fifty-eight institutions. The aim of the analysis was to develop a license model for subscription purchases. The results show that journal use followed the "80/20 rule" or Pareto principle. The conclusion is that, for a cost-benefit license model, institutions should be grouped into three or four categories based on their subject fields and amount of use. The article also discusses the problem with usage data and highlights the need for implementing a system to locally collect and analyze usage data rather than relying on the usage data provided by vendors and publishers.