Sharing an app without oversharing

You made an app for five people. Posting a link in a group chat and hoping nobody forwards it isn't a plan. A shared password is worse: you can't take it back from one person.

Share with a link, a QR code or an email invite. A link can be for one person or open, and it can expire. Every new device then waits for you to approve it.

Turn off a person or a device and the app locks the next time it checks in. Nobody else is affected.

The honest limit: it can't reach into someone's machine and delete files. It closes the door from then on.