Premium features enabled after device change

[SvanderWoude]

While listening to Spotify on my phone I arrived at the office and switched to my laptop using the "Listen on device" option. When I left the office I switched it back to my phone in order to listen music while going home. I noticed that I was able to go back to the previous song and skip an unlimited amount of songs. I do not have a premium account, therefor I should not be able to do those things. I think it has something to do with the device switch enabling the controls when listening on my laptop, which did not get switched back when switching to my phone.