None Premium Accounts able to play as much as possible on singleplayer.

So if you download the minecraft application onto your desktop either through a premium account or just download it from a torrent site you can use a account which isn't premium to play in singleplayer. I found this out when I was messing about with my minecraft account and I could use my non premium account to play in singleplayer. I don't think you can play on multiplayer or play in LAN. The player doesn't have a username above their head and the character has Steve skin by default (dunno if its changeable). this allows people to play as much singleplayer as they want without buying the game and they don't have a timer like on the demo version on the website.

Hope this helps and I hope this bug gets fixed and please fix this as fast as possible. Thanks