If you would like to have a report that shows the last time a ticket has been updated, you can follow the steps below:
Create a custom field in Admin > Tickets Structure > Fields and select the Date field and give this a title
Once the Field has been created you can create a new trigger (Admin > Business rules > Triggers) for both New Replies and Ticket Updates copying the below. Ensure that you have ticked ‘Use advanced formatting’ In order for the
{{ 'now'|date('Y-m-d') }}
formula to work:

If you would like to have a report to view the most recent changes then simply build the following:
SELECT tickets.id, tickets.custom_data[33]
FROM tickets
WHERE tickets.custom_data[33] = ${date} AND tickets.custom_data[33] > '0'
ORDER BY ${date} ASC

Having this set up will allow you to view which tickets that have been updated most recently. You can tweak the triggers and the report to show more specific information if you need it to. If you have any issue with this please contact support at support@deskpro.com