Forms Claims Authentication

 var formsAuthOption = SPFormsAuthenticationOption.None;
            var tokenType = SPSessionTokenWriteType.WriteSessionCookie;
             if (rememberme)
                 {
                     formsAuthOption = SPFormsAuthenticationOption.PersistentSignInRequest;
                    tokenType = SPSessionTokenWriteType.WritePersistentCookie;
                 }
    var settings = SPContext.Current.Site.WebApplication.IisSettings[SPContext.Current.Site.Zone];
             var authProvider = settings.FormsClaimsAuthenticationProvider;
             var securityToken = SPSecurityContext.SecurityTokenForFormsAuthentication(new Uri(SPContext.Current.Web.Url), authProvider.MembershipProvider,authProvider.RoleProvider, "test123",  "password", formsAuthOption);
             
  var fam = SPFederationAuthenticationModule.Current;
            fam.SetPrincipalAndWriteSessionToken(securityToken, tokenType);