I’m a hobbyist at best, so the subscription is not justified or useful for me (plus I just don’t like subscriptions). I wish you guys had some intermediate product that allowed a one-time contribution through the App Store. Anyway, thanks for such a great app!
If you're looking for a polished mobile SSH client without a subscription model, you might be interested in Blink[1]. It's worth mentioning that in addition to SSH, it also supports Mosh[2] (it's the official iOS client!), a remote access protocol tailored to handle spotty mobile connections. It's also open source[3] and gives you access to several Unix commands offline.
[2] https://mosh.org