By default, Slack lets any member install and remove apps in your workspace. That can lead to two problems:
Matter gets removed by someone who didn't realize the whole team relies on it
Matter gets added to another channel, which creates a separate Matter workspace with its own settings, members, and billing, including its own free trial. On a paid plan, this often looks like your account changed or reverted to a trial, when a second workspace was actually created alongside the original.
Who can use this: Workspace Owners and Admins on every plan. Slack only. Using Microsoft Teams? See Control who can add Matter to Microsoft Teams channels.
For an overview of the whole feature, read the Matter setup and rollout guide for Slack and Microsoft Teams. Related articles: Transfer Matter to a new channel in Slack and Microsoft Teams and Using Matter with Slack Connect.
Requiring app approval solves both. Once enabled, only workspace owners, admins, and people you designate can add or remove apps, including Matter.
đĄ Unlike Microsoft Teams, Slack keeps these controls separate from app usage. Requiring app approval does not affect anyone's ability to give kudos, redeem rewards, or otherwise use Matter.
Enable Require App Approval
Access Workspace Settings
Open the Slack desktop application.
Click your workspace name in the sidebar.
Navigate to App Management
Hover over Tools & settings, then select Manage apps.
Adjust App Approval Settings
Click App Management Settings in the left column.
Toggle the switch next to Require App Approval to enable it.
With this setting enabled, only your Slack workspace owners and the people you specify can install or remove Matter. This helps ensure Matter remains a consistent and valuable tool for your team.
Slack's documentation: Manage app approval for your workspace
Good to know
Existing apps stay installed. Turning on app approval doesn't remove anything already in your workspace; Matter continues to run normally.
This won't stop a workspace owner from adding or removing Matter. Who holds owner and App Manager rights is the real control point.
Enterprise Grid customers have additional controls. See Enterprise Grid: control who can add Matter in Slack and Microsoft Teams.