Packages can be loaded/unloaded. IUnloadableService interface added whose method Unload, if service implements it, will be called when the module is unloaded.

NadekoBot.Modules.Gambling/Services/AnimalRaceService.cs

@@ -0,0 +1,21 @@
+using System.Threading.Tasks;
+using NadekoBot.Services;
+using System.Collections.Concurrent;
+using NadekoBot.Modules.Gambling.Common.AnimalRacing;
+
+namespace NadekoBot.Modules.Gambling.Services
+{
+    public class AnimalRaceService : INService, IUnloadableService
+    {
+        public ConcurrentDictionary<ulong, AnimalRace> AnimalRaces { get; } = new ConcurrentDictionary<ulong, AnimalRace>();
+
+        public Task Unload()
+        {
+            foreach (var kvp in AnimalRaces)
+            {
+                try { kvp.Value.Dispose(); } catch { }
+            }
+            return Task.CompletedTask;
+        }
+    }
+}