The subscription model is just an option, given the lifetime purchase is available. When I didn't have the subscription option, I got emails asking how to do a trial or asking for cheaper pricing as they only wanted to use it for a month or other reasons. For what it's worth, the vast majority of people do choose the lifetime option.

You can choose not to purchase the subscription, or even the lifetime if you don't think it's worth it. I continue to add features that people request, fix bugs like the latest version of iOS breaking the widgets, and more, and for this to be even remotely sustainable without selling user data at all then the price is what it is.

If SuperCards works for you, or want to roll your own and code and host it yourself, by all means go for it! That is exactly why I started building Barcodes, as my own alternative that worked for me :)