Arctic is phenomenal. My go to lemmy client and every bugfix on the 0.4.x release has made me really happy to be using it. Personally I would happily pay a yearly sub for it when it’s out of testing.
Sorry for the late response, I had overlooked your post.
Thank you so much, I’m really glad you’re enjoying Arctic! I have looked into adding subscription options, and as far as I can tell, Apple does not allow subscriptions without offering subscription based content or features. This goes against Arctic’s pay if you want modal, so currently I do not plan to add subscriptions. I am planning to reach out to AppStore support and see if I’ve overlooking something in the guidelines that allows subscription based tips.
If not, I do offer one time in-app purchases in Arctic’s settings that allow for leaving a tip.
You can install the App Store version, use the tip jar, and then switch back to the TestFlight version without losing any settings. That’s what I do occasionally.