You could use the log parser tool and run below query to get the number of unique visitors for your site:
SELECT DISTINCT date, c-ip
INTO tmp.txt
FROM 'C:\LogFiles\web\ex*'
SELECT date, count(c-ip) AS UniqueVisitors
INTO Unique.txt
FROM tmp.txt
GROUP BY date
To run these two, you can either download the files and use this syntax:
logparser file:UniqueVisitors1.sql -i:W3C -o:W3C
logparser file:UniqueVisitors2.sql -i:W3C -o:NAT -rtp:-1
Or type the query as an argument to logparser.exe, for example:
logparser "SELECT DISTINCT date, c-ip INTO tmp.txt FROM 'C:\LogFiles\web\ex*'" -i:W3C -o:W3C
And the same with the second query.
As you have probably already figured out, you need to replace "C:\LogFiles\web\ex*" with the path to where you store your log files.
You could download log parser from below link:
https://www.microsoft.com/en-us/download/details.aspx?id=24659
reference link:
counting unique visitors with flask
https://support.microsoft.com/en-us/help/910447/log-parser-2-2-and-asp-net
How do I count unique visitors to my site?