Find a contact's last subscription date
Go to Audience > Contacts.
Search for and select the contact email address or mobile number, or select the Edit icon.
The date of their most recent subscription is displayed on the left side of the Overview tab.
Read more in Single customer view.
If a contact unsubscribes and then resubscribes, the date of the resubscribe is shown.
Contacts subscribed prior to 15 October 2014 always display Unknown.
Manually add a subscribe date
You can manually enter a subscribed date for a contact — perhaps because it's set to Unknown, or if you know the date you have is incorrect.
To do this:
Go to Audience > Contacts.
Search for and select the contact email address or mobile number, or select the Edit icon.
On the Overview tab, select the date (or Unknown if that's the case), to open the Last subscribed date side panel.
Expand the Date drop-down menu and choose a date.
Select APPLY.