How to maintain a conversational state

Recently, I wrote a dialogue assistant based on rasa version 3.2, but the problem is that this service deals with the dialogue information of Line (a communication tool used in Taiwan, Japan and South Korea), so my rasa service can only calculate the messages sent by users one by one. , which leads to the fact that when processing the current latest user dialog, the information such as the slot reserved by the previous dialog cannot be used. What should I do? What should I do?

Help Me, Please !

Each user should have a unique sender_id (set via the channel).