You may be able to purchase insurance in South Carolina without changing your California license but according to SC state laws you will need to change your driver's license to a SC license within 3 months of moving to South Carolina.

The SC Department of Motor Vehicles (SCDMV) notes that if you are a new resident, you may use a valid driver's license from your former state for up to 90 days. However, you MUST convert to a South Carolina driver's license before the end of the 90-day period.

If your driver's license from your home state has expired, you must also pass the knowledge and road tests. To schedule a road test, you should call the DMV office where you would like to take the skills test.

South Carolina law dictates that each qualified driver can have only one driver's license. You may not have a valid license from South Carolina and another state. To qualify for a SC driver's license, you must pass the eye exam given at all DMV offices or submit a statement of visual acuity from an eye specialist. A South Carolina license is valid for ten years and must be renewed by your birthday in the tenth year.

So while you may be able to buy, register and get insurance with your California license while in South Carolina if you plan to do so after 90 days of living in South Carolina you will need to obtain a SC driver's license in order to follow SC law.