Will I be able to get app updates if iCloud Family sharing is turned off ?

We had iCloud family sharing turned on, I downloaded the app Notability from my brother's purchases, he has turned off iCloud family sharing recently,

Q1)Will I be able to use the app? Its yes for now...

Q2)Will I be able to get the app updates for Notability app?

Q3)Once if I uninstall Notability App, is there any way I can get it back?

Q4) Is there a possibility of losing the app if I apply a major macOS update or iOS update

I called up Apple support they couldn't help...