Status of the Roles and Responsiblities in Oracle

Excepted:
      Roles and Responsibilities is meant to active for the period, You have just given for the User.
      But, You can assign a role for an user that would be assigned infinitely long by just leaving the 'Active To' Field as Blank.
To Roles and Responsibilities:
      Login as SYSADMIN/SYSADMIN, Go to User Management-->Users, click 'Assign roles' button.