Welcome, but remember that in Europe we don't subscribe to "Europe: love it or leave it", the left because of the "leave it" and the right because of the "love it".

By the way, membership in a European party is quite different from voter registration in the US. It qualifies you as an activist whereas a US registered voter is just a sympathiser. A few years ago the Spanish Socialist party realized they could benefit from keeping track of sympathisers as well as members (whom we call "militants" is Spain, actually). You will also find that voter registration is pretty much automatic in Europe.

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman