Right, having been to Docklands today and got royally fucked up the arse for a peak time travel card I've decided it may be best to get an Oyuster card thingy. Now, I very rarely use public transport now but every other fucker's got one and they're cheaper so I thought I might as well join the 'in' crowd rather than paying double what everyone else does.

Question - do you only have a limited time in which to spend the money on it ? My thought is to get a card, shove a score or so on it and leave it in my wallet. If I ever need it, Bob's your mothers uncle and no messing about.

Is this the case or does it 'expire' ?