They are perennial plants. They will live and grow for years but the ones that get tall are not the ones you get in garden centers. those are bred to be sold as annuals, although I have had some for 2 years now and they are alive and well.
The ones in Greece are the ones you get from nurseries. They are not disturbed by snow and frost so they just grow and grow. They do not have lots of leaves, just a trunk and some branches but i love them. full of character!!!
The tall one I had in England was just a pellie that was grown a bit like a standard plant, not allowed to have lots of side branches.