.net web api Bearer token exipres within a few minutes

Question

I've set up Web API + oauth2 bearer token authentication successfully. I get a token via the /authtoken endpoint and can use it for calls to protected areas of the web api.

However, I have set the expiration on 7 days, but the token seems only valid for about 5 minutes:

 public void ConfigureOAuth(IAppBuilder app)
        {
            OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
            {
                AllowInsecureHttp = true,
                TokenEndpointPath = new PathString("/authtoken"),
                AccessTokenExpireTimeSpan = TimeSpan.FromDays(7),
                Provider = new SimpleAuthorizationServerProvider()
            };

            app.UseOAuthAuthorizationServer(OAuthServerOptions);
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
        }

What could be wrong here?

Answer 1

Weird, adding a machine key to the web.config fixed it. I'm not using different servers nor different webapps so why adding a machine key works beats me, but I guess it's good practice anyway.