You can also use the license API to retrieve the currently installed license:
curl -XGET -u elastic:changeme 'http://<host>:<port>/_xpack/license'
{
"license" : {
"status" : "active",
"uid" : "0a98411f-73f4-4c67-954c-724874ed5488",
"type" : "trial",
"issue_date" : "2015-10-13T18:18:20.709Z",
"issue_date_in_millis" : 1444760300709,
"expiry_date" : "2015-11-12T18:18:20.709Z",
"expiry_date_in_millis" : 1447352300709,
"max_nodes" : 1000,
"issued_to" : "elasticsearch",
"issuer" : "elasticsearch"
}
}
You need cluster admin privileges to retrieve the license.