Well you can use RescueTime which comes in free as well as pro versions.
RescueTime helps you figure out the answer by showing you how you spend your time on the computer.
Or else you can use HomeGuard too.
HomeGuard is an advanced parental control and activity monitoring tool for family and child safety online and offline. Once installed HomeGuard will silently and automatically block all pornographic and inappropriate content online and record detailed website activity including time of visit and time spent on each website.
Plus a built in keylogger, activity based screenshots, chat and email monitoring and filtering, program/games blocking and time restrictions, Internet and computer usage time restrictions, email notifications and more. HomeGuard is virtually impossible to tamper with, it cannot be bypassed using proxy servers and is unclosable and uninstallable unless the administrative password (provided during installation) is used.