Short answer: With Still Dock Plus on that Mac, Still Dock for iPhone and Apple Watch switches the Mac's Stop ⌘Q quitting protection on or off from your phone, your wrist or Siri, for any Mac signed into the same Apple Account, without walking over to it.
Still Dock for iPhone and Apple Watch is on the App Store, on the same listing as Still Dock for Mac.
On your own Mac, ⌘Q quitting the wrong app is annoying but you're standing right there to switch the guard on. On a family Mac, a classroom Mac, or a front desk machine, you often aren't. Someone else is at the keyboard, and by the time you notice their work got closed by a stray ⌘Q, it's too late to fix from across the room.
Being able to flip that lock on from your phone means you don't have to walk over, and you don't have to give anyone your Mac's own unlock credentials just to turn on a keyboard guard.
Stop ⌘Q quitting holds the shortcut per app you choose, so ⌘Q keeps working everywhere else. The installer version holds the key down; the App Store version asks you to press it twice. Either way, the app you protected stops closing on one accidental tap. See how Cmd Q works and why it has no built-in undo for the Mac side of this in full.
Open the app, choose the Mac from the list, and switch Stop ⌘Q quitting on. You can also ask Siri on your iPhone. Your Mac applies the change through the same code as its own menu bar switch, with no separate remote-only behavior to learn.
Turning it back off is the one that asks first: Face ID on your iPhone, and if that Mac itself needs Touch ID or a password to unlock, it asks there too. Nothing turns off silently just because a phone sent a request.
Your iPhone, Apple Watch and Mac share this setting the same way they share the rest of Still Dock's settings, through your own iCloud account. Signing in to a Still Dock account is optional, with Apple or your email. Signed in, your email address goes to the Still Dock server, which checks your plan and keeps a backup of your settings. Which locks are on, your Mac's name and its version still travel only through your own iCloud account.
Yes. Every Mac signed into the same Apple Account shows up on its own, with its own switch. Turning it on for the kitchen Mac doesn't touch the one in the office.
Only the effect: ⌘Q stops instantly quitting the apps you've protected. There's no pop-up announcing that a phone made the change.
Yes. The iPhone and Apple Watch app is on the App Store, on the same listing as Still Dock for Mac.
It applies once the Mac wakes and checks in, as long as that's within about 10 minutes. Older than that, the request is never applied late, so it simply expires and surprises nobody hours afterward.
For the wider picture, see controlling your Mac's Dock from your iPhone, and for locking a Dock other people use day to day, how to lock the Dock on a shared Mac or on a family Mac.