Conversations often need a clear ending rather than an abrupt disappearance. You can say, "It was good to talk with you. I need to get back to my class now." The reason can be brief and truthful.
If there is a real next step, confirm it: "I will send you the reading list this evening." Avoid making a promise only to soften the ending. "I will see you at the next session" is useful when that shared session actually exists.
Close the current exchange
Practice this sequence. You: "I should leave in a moment. Was there anything else we needed to decide?" Partner: "Just the meeting place." You: "Outside the main entrance at nine. Thanks; see you then." The closing also resolves an unfinished practical point.
For an informal chat with no arrangement, "Nice talking with you. Enjoy the rest of the event" can be sufficient. You do not need to offer a future meeting whenever a pleasant conversation ends.
Record two versions: one with a colleague after discussing a task, and one with a new acquaintance. Check that your tone and detail suit each relationship. A useful ending leaves both people clear about whether anything is expected afterward, while giving the other person a moment to acknowledge the close and say goodbye.