**Service areas** on highways and expressways are designed for drivers to **stop or park** safely. However, **free circulation** in these areas is not allowed. This is because they are exclusively intended for rest and services, not for the continuous transit of vehicles.

- **Stopping and parking** on highways or expressways is only allowed in rest or service areas, but not for circulation.
- Service areas are spaces where drivers can stop to rest, refuel, or use other services, but not to use them as circulation routes.

Therefore, the correct answer is that it is **not allowed** to use service areas for free circulation.