How are bearer tokens stored server-side in Web API 2?

I am setting up bearer token authentication in Web API 2, and I don't understand how (or where) the bearer token is being stored server-side. Here is the relevant code:

Startup:

public partial class Startup
{
    public static OAuthAuthorizationServerOptions OAuthOptions { get; private set; }
    public static Func<UserManager<IdentityUser>> UserManagerFactory { get; set; }
    public static string PublicClientId { get; private set; }

    static Startup()
    {
        PublicClientId = "self";
        UserManagerFactory = () => new UserManager<IdentityUser>(new UserStore<IdentityUser>());
        OAuthOptions = new OAuthAuthorizationServerOptions
        {
            TokenEndpointPath = new PathString("/Token"),
            Provider = new ApplicationOAuthProvider(PublicClientId, UserManagerFactory),
            AuthorizeEndpointPath = new PathString("/api/Account/ExternalLogin"),
            AccessTokenExpireTimeSpan = TimeSpan.FromDays(14),
            AllowInsecureHttp = true
        };
    }

    public void ConfigureAuth(IAppBuilder app)
    {
        // Enable the application to use a cookie to store information for the signed in user
        app.UseCookieAuthentication(new CookieAuthenticationOptions());

        // Use a cookie to temporarily store information about a user logging in with a third party login provider
        app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

        app.UseOAuthBearerTokens(OAuthOptions);
    }
}

WebApiConfig:

public class WebApiConfig
{
    public static void ConfigureWebApi()
    {
        Register(GlobalConfiguration.Configuration);
    }

    public static void Register(HttpConfiguration http)
    {
        AuthUtil.ConfigureWebApiToUseOnlyBearerTokenAuthentication(http);
        http.Routes.MapHttpRoute("ActionApi", "api/{controller}/{action}", new {action = Actions.Default});
    }
}

AuthUtil:

public class AuthUtil
{
    public static string Token(string email)
    {
        var identity = new ClaimsIdentity(Startup.OAuthOptions.AuthenticationType);
        identity.AddClaim(new Claim(ClaimTypes.Name, email));
        var ticket = new AuthenticationTicket(identity, new AuthenticationProperties());
        var currentUtc = new SystemClock().UtcNow;
        ticket.Properties.IssuedUtc = currentUtc;
        ticket.Properties.ExpiresUtc = currentUtc.Add(TimeSpan.FromMinutes(30));
        var token = Startup.OAuthOptions.AccessTokenFormat.Protect(ticket);
        return token;
    }

    public static void ConfigureWebApiToUseOnlyBearerTokenAuthentication(HttpConfiguration http)
    {
        http.SuppressDefaultHostAuthentication();
        http.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));
    }
}

LoginController:

public class LoginController : ApiController
{
    ...

    public HttpResponseMessage Post([FromBody] LoginJson loginJson)
    {
        HttpResponseMessage loginResponse;
        if (/* is valid login */)
        {
            var accessToken = AuthUtil.Token(loginJson.email);
            loginResponse = /* HTTP response including accessToken */;
        }
        else
        {
            loginResponse = /* HTTP response with error */;
        }
        return loginResponse;
    }
}

Using the above code, I'm able to login and store the bearer token client-side in a cookie, and then make calls to controllers marked with [Authorize] and it lets me in.

My questions are:

Where / how is the bearer token being stored server-side? It seems like this is hapenning through one of the OWIN calls but I can't tell where. Is it possible to persist the bearer tokens to a database server-side so that they can remain in place after a Web API server restart? If the answer to #2 is no, is there anyway for a client to maintain its bearer token and re-use it even after the Web API goes down and comes back up? While this may be rare in Production, it can happen quite often doing local testing.