Currently, AdWords API v201409 is not deprecated, so your calls should be succeeding. I suppose the best way to programmatically tell if a version is deprecated is to try to make a call to it and see if you get an error message. There is no way to look up when a version is going to be deprecated in the future, however, so in order to make sure that you have enough time to migrate, you should either follow
our blog, where we will announce all sunsets in advance, or check the
sunset dates page on our developers site.