Change premium app subscription timeframe?

Hi,

I haven’t used many subscription service apps but there’s one that I’d like to upgrade. There are three options: monthly, yearly, and lifetime. What I’d like to do is get a one month premium upgrade and if I like it as much as I think I will, then cancel the monthly sub and get lifetime.

Having not dealt with iOS app subs before, is this even possible to do? I’ve reached out to the app dev directly and am waiting to hear back but I wondered if the protocol might be the same way for all apps on this anyway meaning maybe one can always switch up the subscription length). So I thought I’d ask here.

Thanks so much for any help!! I really appreciate it. :)