Do not worry about frosts damaging the beans for next year's plants. I have picked pods off the ground or the soil in pots in the spring after the pods and the beans in them have been lying there all winter and have planted them successfully.
Indeed, the plants came up as mightily as ever.
On the other hand, if you are the orderly type and like to be sure about your chances - do pick the pods and let the beans dry in the pods. They will shrivel up and trun beige. Seal them in a zip-lock bag and wait till the spring. Then you want to pick out the hard black beans with the one white slitty eye and plant them after ascertaining that there is no danger of frost.
If you really want lablabs in the winter, you can even plant them indoor as house plants.
I've grown Dolichos lablab for years now, all my plants were from two pods picked off the vine on a visit to a friend of a friend's garden. I've given many many pods to friends who've given pods away and so forth.