HttpClient does not return anything

using (var httpClient = new HttpClient())
{
    httpClient.Timeout = TimeSpan.FromSeconds(5);
    
    httpClient.DefaultRequestHeaders.Add("licenseKey", licenseKey);
    httpClient.DefaultRequestHeaders.Add("customerKey", customerKey);
    string url = "http://localhost:3001/api/myTool/license/register";
    HttpResponseMessage response = await httpClient.GetAsync(url);
    if (response.IsSuccessStatusCode)
    {
        string responseBody = await response.Content.ReadAsStringAsync();
        JObject json = JObject.Parse(responseBody);
        
        return json["expiresOn"]?.ToString();
    }
    else
    {
        return null;
    }
}