>I thought I used to be able to use the 'Online' dropdown to see a list of members currently on line.
>Is that a 'subscription only' option ?

The upper toolbar can be configured to a certain extent - see image attached

I think it used to be in the 'Update your account' for non subscribed users, but I don't find it there anymore

But I now find it in 'Update your account' for subscription - try to look there