Views Counter - Current User

Hello everybody,
I am trying to create a “View counter” Everytime a Current User (not signed or logged in) is viewing my page, will be count on the counter.
So what I did is to save is Current User unique’s id , in a list, and do a count of the list itself. It’s gonna add the current user id only when is not in the list, to avoid repetition.
The problem though it is when a current user is not viewing the page anymore. What I thought was "if the list doesnt contain anymore that Current user unique ID , then delete that particular Id , so the counter should reflect the users actively being on my page.
The Workflow works, it is deleting the right id, however it does it as soon as I open the same page with another device (device n2), as it thinks now the current user is the new device connected, despite the fact that the device n1 is still on the same page.
Where did I fail ?

As always,
Thank you