Tesla has started sending messages to existing Model 3 and Model Y owners in multiple regions worldwide, stating that if they want to transfer their previously purchased Full Self-Driving (FSD) permanent service to a new car, they need to complete the delivery of the new car by March 31. For owners without permanent FSD, the deadline to purchase it for a new car is also the same date. This move comes after Musk announced that the service will switch to a monthly subscription model instead of a one-time permanent purchase.