How to load and completely unload third-party C# plugins from RAM without restarting the host process:

public class PluginLoadContext : AssemblyLoadContext
{
    public PluginLoadContext() : base(isCollectible: true) { }
}

// Loading & Unloading
var context = new PluginLoadContext();
Assembly pluginAssembly = context.LoadFromAssemblyPath("/plugins/CustomTool.dll");
// Execute plugin logic...

context.Unload(); // Unloads assembly and frees metadata from memory!
GC.Collect();
GC.WaitForPendingFinalizers();

isCollectible: true allows the Garbage Collector to fully reclaim JIT-compiled code and type metadata.

Crucial tip: Ensure zero references (instances, delegates, types) remain in the host process, or the ALC will stay pinned in memory.

Used this to implement hot-reloading game scripts in our engine without restarting server processes.