The producer of podcasts (and lots of other things) Slate has a membership program called Slate Plus. Many of the podcasts produces by Slate give members access to extra material and even full episodes that are members only. I listen to podcasts using Spotify, including Slate's podcasts. However, I cannot access the members only episodes through Spotify. Other podcast apps have the possibility to enter a code or special URL (provided by Slate) that gives access to members only material. Spotify should have this feature as well.