Driving without insurance is a serious offense in most states. If your friend was notified that her license plates were to be turned in last year and did not comply, her penalties will likely be quite harsh. It depends on what specific state she is licensed in as to what her exact penalties will be.
For example in New York, you can be arrested, ticketed and have your vehicle impounded if you are found driving without insurance. If you are uninsured and do not follow the steps required of you, your vehicle registration will be suspended and the license plates must be turned into the DMV.
The NYS registration suspension will last for the same number of days the vehicle was without liability coverage and the plates were not turned in. If the registration suspension period is more than 90 days, the person's driver's license will also be suspended.
In Delaware, if you do not surrender your license plates when you cancel or have a lapse in car insurance you will owe $100 per vehicle for being uninsured 1 - 30 days and an additional $5 per vehicle each day after 30 days.
You can check with your state's Department of Motor Vehicles to find out what your state penalties are for driving uninsured.