Tinder "last active" refers to the time that a particular person was last online “swiping” on the dating app.
There is sometimes confusion about what this time and date mean, as people often presume it refers to when the person was last logged into Tinder... but it doesn't!
Last active will only update if the user is going through the recommendations and swiping left or right, rather than just messaging people or innocently opening the app.
The great thing about this is that, if you are talking to someone and getting along, you can see if they are continuing to keep their options open and looking at other people!
Well, I say great... If you check the person's profile the day after a date and it shows that they were last active 12 hours ago, you may want to rethink suggesting a second date!