It might be a bit complicated to find the necessary piece of information in a long conversation in a direct channel. If you want to structure one-to-one communication, it's possible to create Topic channels under Direct channels and discuss some subjects separately. You can create several Topic channels under 1 Direct channel so it'll be easier to find the information you have talked over.
How to create a topic channel:
Option 1:
click on 3 dots next to a direct channel name;
select New Topic;
Fill in the Position and Display name fields, Channel description and sorting (optionally).
A Topic channel is created!
Option 2:
Click on the user's icon in the chat area;
Click "New > Topic";
Fill in the Position and Display name fields, Channel description and sorting (optionally).
A Topic channel is created!
You can create several Topic channels under 1 Direct channel.