You can see all texts a subscriber has sent or received by creating a Report. This report is an exported CSV file that shows details about the texts this person has sent and received.
Head to Settings > Reports > Subscriber Texts.
Select a date range and the subscriber you'd like to see data on.
Click Create Report.
This report will show the date and time of each incoming and outgoing text to that specific subscriber. This includes any workflow texts, inbox messages, replies, and texts within subaccounts if you'd like.