.ps1 cannot be loaded because the execution of scripts is disabled on this system

I run this code to execute PowerShell code from an ASP.NET application:

System.Management.Automation.Runspaces.Runspace runspace = System.Management.Automation.Runspaces.RunspaceFactory.CreateRunspace();
runspace.Open();
System.Management.Automation.Runspaces.Pipeline pipeline = runspace.CreatePipeline();
pipeline.Commands.AddScript(@"\\servername\path");

pipeline.Commands.Add("Out-String");

Collection<PSObject> results = pipeline.Invoke();

runspace.Close();

But I am getting an error:

.ps1 cannot be loaded because the execution of scripts is disabled on
this system. Please see “get-help about_signing” for more details.

The same code runs fine from a command prompt or a windows (Windows Forms) application.