Embodiments of the disclosure provide user equipment (UE) performing unicast sidelink communication with the second UE and methods therefor. A method of a first UE that performs direct sidelink communication with a second UE includes: receiving a first indication comprising sidelink signalling; in response to receiving the first indication, performing at least one of: updating a configuration for performing a transmission/reception procedure of the first UE in order to update a key based on the updated configuration for performing a transmission/reception procedure; suspending at least one data transmission/reception procedure; and resuming at least one data transmission/reception procedure. Accordingly, the UE may control resumption of transmission/reception on the sidelink such that transmission/reception on the sidelink is only resumed when a key is appropriately updated, thereby avoiding a situation where the UE transmits a message using a key and the second UE attempts to receive said message using a different key.