The Spotify client is auto-updating, so you will always be on the most recent version without needing to do anything. As soon as there is a new version available to you, the client will download and update, showing the update bar if you happen to be online when it does so. So why are version numbers even relevant?
It's relevant if you want to diagnose whether the app is auto-updating correctly. In my case, it wasn't.
Rather than just checking what the most current version number was against what Spotify on my Mac was reporting, I was forced to deduce it was out of date by the fact users on forums were discussing Spotify versions which were more advanced than the one I had.
I did a fresh install and, sure enough, I now have a version of Spotify which is v0.9.1.57. This is quite a jump from v8.3.222 which is what it was reporting just prior to the fresh install.
Interestingly. The new version seems to have installed itself, without prompting me for a location, in /Users/<USER>/Applications/... rather than in /Applications/... which is where all of my other apps are installed. I now have two versions of Spotify installed.
In any case, it would have been useful to have known the version number of the current release.
Exactly. Mine isn't updating properly. I even went to Spotify and reinstalled it and it keeps getting stuck on an older version. I get the message to restart to install the latest version, but when it restarts, the notice is there again and when I check, the version hasn't changed. So, yes, it would be helpful if Spotify posted what the latest version is and a file to install it.