Labour Leadership 2016

That's the fee to become a registered supporter. Membership is diffrent.

http://www.labour.org.uk/pages/questions-about-membership
https://join.labour.org.uk/

We’ve got a wide range of rates so you might pay as little as £1 a
year. Our standard rate starts at £3.92 a month and you can choose to
pay more if you wish, as many of our members do.

Unlike the Tories, we don’t rely on a small number of super-wealthy
donors. We rely on funds from our dedicated members and your
membership fee would provide a vital boost to our campaigning efforts.
Without that money, we simply wouldn’t be able to run the Labour
Party.