Runner beans are also called seven year beans in the US as they are a perennial plant. They are probably too tender to survive the Winter in the UK unless well protected though. You should find a good strong root system when you dig them up at the end of the season.
If you leave some beans to mature they will give you lovely large fresh beans which you can freeze, just wait until you can see the swollen beans inside the pods. If you have enough time and good weather let the pods dry out on the vine for dry beans which can be stored in a jar.