diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index cbb91e66..f5ff5763 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -478,6 +478,7 @@ public class Controller extends Thread {
 		ArbitraryDataBuildManager.getInstance().start();
 		ArbitraryDataCleanupManager.getInstance().start();
 		ArbitraryDataStorageManager.getInstance().start();
+		ArbitraryDataRenderManager.getInstance().start();
 
 		// Auto-update service?
 		if (Settings.getInstance().isAutoUpdateEnabled()) {
@@ -1069,6 +1070,7 @@ public class Controller extends Thread {
 				ArbitraryDataBuildManager.getInstance().shutdown();
 				ArbitraryDataCleanupManager.getInstance().shutdown();
 				ArbitraryDataStorageManager.getInstance().shutdown();
+				ArbitraryDataRenderManager.getInstance().shutdown();
 
 				if (blockMinter != null) {
 					LOGGER.info("Shutting down block minter");
diff --git a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataRenderManager.java b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataRenderManager.java
index ca98c484..483ab92f 100644
--- a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataRenderManager.java
+++ b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataRenderManager.java
@@ -1,20 +1,22 @@
 package org.qortal.controller.arbitrary;
 
 import org.qortal.arbitrary.ArbitraryDataResource;
+import org.qortal.utils.NTP;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Objects;
+import java.util.*;
 
-public class ArbitraryDataRenderManager {
+public class ArbitraryDataRenderManager extends Thread {
 
     private static ArbitraryDataRenderManager instance;
+    private volatile boolean isStopping = false;
 
     /**
-     * List to keep track of authorized resources for rendering.
+     * Map to keep track of authorized resources for rendering.
+     * Keyed by resource ID, with the authorization time as the value.
      */
-    private List<ArbitraryDataResource> authorizedResources = Collections.synchronizedList(new ArrayList<>());
+    private Map<String, Long> authorizedResources = Collections.synchronizedMap(new HashMap<>());
+
+    private static long AUTHORIZATION_TIMEOUT = 60 * 60 * 1000L; // 1 hour
 
 
     public ArbitraryDataRenderManager() {
@@ -28,17 +30,46 @@ public class ArbitraryDataRenderManager {
         return instance;
     }
 
+    @Override
+    public void run() {
+        Thread.currentThread().setName("Arbitrary Data Manager");
+
+        try {
+            while (!isStopping) {
+                Thread.sleep(60000);
+
+                Long now = NTP.getTime();
+                this.cleanup(now);
+            }
+        } catch (InterruptedException e) {
+            // Fall-through to exit thread...
+        }
+    }
+
+    public void shutdown() {
+        isStopping = true;
+        this.interrupt();
+    }
+
+    public void cleanup(Long now) {
+        if (now == null) {
+            return;
+        }
+        final long minimumTimestamp = now - AUTHORIZATION_TIMEOUT;
+        this.authorizedResources.entrySet().removeIf(entry -> entry.getValue() == null || entry.getValue() < minimumTimestamp);
+    }
+
     public boolean isAuthorized(ArbitraryDataResource resource) {
         ArbitraryDataResource broadResource = new ArbitraryDataResource(resource.getResourceId(), null, null, null);
 
-        for (ArbitraryDataResource authorizedResource : this.authorizedResources) {
-            if (authorizedResource != null && resource != null) {
+        for (String authorizedResourceKey : this.authorizedResources.keySet()) {
+            if (authorizedResourceKey != null && resource != null) {
                 // Check for exact match
-                if (Objects.equals(authorizedResource.getUniqueKey(), resource.getUniqueKey())) {
+                if (Objects.equals(authorizedResourceKey, resource.getUniqueKey())) {
                     return true;
                 }
                 // Check for a broad authorization (which applies to all services and identifiers under an authorized name)
-                if (Objects.equals(authorizedResource.getUniqueKey(), broadResource.getUniqueKey())) {
+                if (Objects.equals(authorizedResourceKey, broadResource.getUniqueKey())) {
                     return true;
                 }
             }
@@ -48,7 +79,7 @@ public class ArbitraryDataRenderManager {
 
     public void addToAuthorizedResources(ArbitraryDataResource resource) {
         if (!this.isAuthorized(resource)) {
-            this.authorizedResources.add(resource);
+            this.authorizedResources.put(resource.getUniqueKey(), NTP.getTime());
         }
     }