Yes, you can purchase modules as per your company requirements. If your primary need is to find out the number of leaves encashed by employees, choose leave reports module. Keep track of the approved/rejected leaves with the leave transaction module. Keep a tab on employee leaves/vacation days/sick leaves with the leave management/holiday calendar module. Basically, you can pick and choose which module you want and build from there or buy the full leave management software complete with all the bells and whistles!