Actually I have been on Pro for several years. However, when I now bought a new cellular, the ZTE Blade III, this device was bundled with 12 months of Spotify Premium via the Swedish operator Telia, So I called off my previous Spotify Premium subscrition and now the "new" subscription via Telia is apparently active.
Since I bought the ZTE with Spotify Premium bundled I find it a bit wierd that Spotify does not even start on this specific device... It works fine on my other devices (PSs,iPod, iPAD, HTC WildfireAndroid cellular.
I was given the tip to install an SD card on the device (there is none at this moment), This would make Spotify work, according to the source. Anyway, I will try it.