Can't select lifetime price in Photomator app

After reading that Apple just purchased Pixelmator and Photomater...

I've downloaded the Photomator application for my Mac from the App Store. It is a free trial for 1 month but it asks you to select how to proceed after that free period. The options were $29 for a whole year, $7.99 per month, and a lifetime of $120. I did see that you could get it for $79 lifetime, but it doesn't seem to be an option from the app in the app store. I selected the monthly option. Once in the app, I went to the "Manage Purchases" menu option and it took me to my Apple subscriptions. There I could not find the "lifetime" option, so I ended up canceling my subscription, which will allow me to use it free for one month, but then not renew. I guess I'll let it expire then try again.

So, a couple of questions, why can't I do the lifetime from in-app purchases? Can I get this from outside of the App Store, and if I do, will Family sharing still work, or is that only an App Store purchase thing?