Active Date Counter (Google Spreadsheets)

This is a weird request, but I wanted to see if anyone knew if what I’m asking is possible, and if so how to do it. If you take a look at the image below, you will see the following columns: Steam Name, Server Status, and Date Last Seen.

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On another sheet, I am importing the details of a server tracker page, (It shows the details of the game server, like how many people are on it, the map, gamemode etc.) That is shown down below along with a link to the site.

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What that sheet (Server Player List) does is that it imports the list of users on the server, then in the Server Status column, if it sees their steam name on the Steam Name column and the Server Player List page, it will mark them as “Online” using the following:

=IF(ISNA(VLOOKUP(D12,'Server Player List'!$ C$ 3:$ C$ 124,1,FALSE)),"Offline","Online")

What I’m trying to do is that if the Server Status is marked as “Online”, it will print the date in the date last seen column. I also want it to stay as that date until it is marked as online again. Meaning I am trying to create an activity tracker, one that will tell me the last time a certain individual logged onto the server. If anyone can help me with this it would be much appreciated.