Unfortunately, no. While we're always thinking of creative ways to allow you more control over your billing cycles, we've yet to find a benefit to pausing your account and/or billing cycle. Here's our thinking...
Pausing an account would immediately kill all RSS and streaming URLs out in the wild—similar to what happens when you delete an account.
Even if you are no longer publishing new episodes, let's say your current show is already listed in Apple Podcasts. Pausing Simplecast's streaming would mean that your listeners who hit the play button would get no audio in Apple Podcasts. Certainly not a ideal outcome.
To retain all past episodes, and the delivery of those files, you must continue with a monthly paid subscription.