@desmiles
All streaming content is provided through a purchased license from the content's owners. (permission to stream/carry on a service). These licenses are purchased for a set time and then expire. Additionally, some content owners only make the availability of their content available for streaming/purchase by services during certain times and then the content becomes unavailable for streaming.
When it comes to the free streaming channels/apps like Roku Channel and others, sometimes this content is carried amongst a few of them at the same time. At other times, it may jump from one service to another so searching for it elsewhere should be the first step if you can't find it somewhere.
There are three seasons of the Flying Nun still currently available for free on Tubi.
https://channelstore.roku.com/details/7c34d32446def64db7eb2cc359749fe5/tubi-tv#!
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
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