Dhiman,
For licensing issues please contact support@optiwave.com, however I think I know the issue. The dongle you have may only be licensed for OptiSystem 13 and not for future updated versions like OptiSystem 14. This would make sense since you say version 13 is still working however OptiSystem 14 will not.
If you do not think this is the issue please contact support@optiwave.com.
Damian