I'm looking for a dongle for my laptop. It's only for very occasional use so I've been looking at Pay As You Go. The ones I've looked at it seems that the data usage which you buy in advance is only valid for 30 days. I'm unlikely to use it all and don't really want to pay for something I won't use. Does anyone more familiar with these matters know if it's possible to just buy a dongle and buy some credit for it which doesn't have a time limit on it?