CuteSoft people did not answer to that post, so I copy here the code I implemented in the case of someone would be interested:

 

public bool AjaxUploaderLicenseFileExists()

{

  // get the web application path
  string apppath = System.Web.HttpContext.Current.Server.MapPath(System.Web.HttpContext.Current.Request.ApplicationPath);
  // get the relative path of the AjaxUploader license file
  string licensefile = System.Configuration.ConfigurationManager.AppSettings["AjaxUploaderLicense"];
  if (string.IsNullOrEmpty(licensefile))
    licensefile = "bin\\AjaxUploader.lic";
  // check if the license file exists
  string licensepath = string.Format("{0}\\{1}", apppath, licensefile);
  return System.IO.File.Exists(licensepath);

}

Anyway, this method only allows me to check wether the license file exists or not, it does not tell me if it is valid (expired or not).

I saw in the AjaxUploader developer guide (http://ajaxuploader.com/document/) that there is a UploaderLicenseProvider.GetLicense Method, but there is no explanation telling how to use it :(...