For choose " Service to Use" ,You have Two option 

1 Project Management + Time Tracker

If you have requirement of agile base project management  software and looking for kanban board .you can choose this option. With this option (Project Management + Time Tracker) you can manage ,assign task to your team member and with the help of time tracker ,you can track your employee.

2 Time Tracker

If you are only looking for time tracker solution for track your employee,you can choose this option.

Note: This is irreversible process ,please choose as per your requirement