You can shape a podcast episode without watching your credit balance.
Drafting a script, rewriting it, auditioning voices, switching templates, and re-rendering all cost nothing. Credits are charged when Jellypod generates something: 1 credit per second of narration, 7 credits per generated image, and 20 credits per generated video clip. Publishing, scheduling, downloading, and re-rendering are free.
So iterate on the script as much as you like, then generate once it reads the way you want. If you change your mind afterwards, regenerating narration is free, and regenerating a single visual costs 7 credits.
Your credit balance carries over unchanged between billing cycles for one month, and purchased top-ups never expire.
For the full picture, see Credits Are Charged When You Generate and Understanding Credits.