The notes tool allows you to leave notes on links so that when you come back to it later on and need to remember what that link was used for, where it was shared, or anything that's important to you regarding that link, you will be able to remember it easily.
To add a note to a short link:
Select the link from the Links page.
Click the Notes icon.
Type your notes in the Add your note field.
Click Add note.
Bear in mind that notes are searchable, so if you need to add product codes, dates, or internal references to your links this is a great option.