Same problem here (southern FI), Qtify one day just stopped working, Premium account only works in my laptop. The error is the same as already listed 'Client upgrade requi...'. And Yaspot simply does not log on (no error).

I am guessing Spotify has started somehow to block the usage of these 3rd party clients, which is a shame, as they haven't come up with their own. This just means they'll lose the money I've put there, have cancelled my subscription due to this.

What a shame...