You should have been given a piece of paper which has an explanation on it.

It lasts for 12 months, if you get another one they take your car away, and you end up paying storage and recovery fees.

My mate sparky fucking loves them, reckons its the best thing ever, cause around here they give you them for drifting, he gets one perhaps once every 10 nights that he goes out drifting on the road, and never gets dangerous driving or anything like that anymore since they started giving out the 59s, so he just figures it costs him 20 quid a night to go drifting on the streets, which is far cheaper than a trackday, and his licence never gets any points.
He's bought his car back 2 or 3 times now