docs: Add LICENSE_MAX_USERS_OVERRIDE usage (#9905)

Author: triklozoid

docs/source/guide/admin_usage.md

@@ -21,6 +21,9 @@ Here you can see the number of seats compared with the number of active users.
 
 Each organization has a set amount of Label Studio seats in their license. To increase your seats, contact your HumanSignal account representative. 
 
+!!! note On-premise
+    On-premise deployments can use fewer seats than their license allows by setting the `LICENSE_MAX_USERS_OVERRIDE` environment variable. It can only lower the licensed seat count, and the deployment does not start if you set it higher. Seats are counted across all organizations in the deployment. See [Available Helm values](helm_values#The-global-extraEnvironmentVars-usage).
+
 ### License info
 
 This section includes general information about your Label Studio license, such as when it was issued and when it expires. 

docs/source/guide/helm_values.md

@@ -324,4 +324,20 @@ global:
 !!! note
     If you are deploying to a production environment, you should set `SSRF_PROTECTION_ENABLED: true`. See [Secure Label Studio](security#Enable-SSRF-protection-for-production-environments). 
 
+<div class="enterprise-only">
+
+### Lower the seat limit of your license
+
+Set `LICENSE_MAX_USERS_OVERRIDE` to use fewer seats than your license allows, for example to keep a staging deployment within a smaller budget:
 
+```yaml
+global:
+  extraEnvironmentVars:
+     LICENSE_MAX_USERS_OVERRIDE: 50
+```
+
+By default this variable is not set and the seat count from your license applies. It can only *lower* that count: if you set it higher than your licensed seats, or below `1`, the deployment fails to start. The license itself is not modified, so removing the variable and restarting restores the licensed seat count.
+
+Because on-premise seats are counted across all organizations in the deployment, the override applies to the whole deployment rather than to a single organization. It also lowers the number of free View-Only seats when your license does not set them explicitly. See [Usage & License](admin_usage#Seats-in-use).
+
+</div>