Update some sections of the admin license page

app/controllers/trials_controller.rb

 class TrialsController < ApplicationController
-  SUBSCRIPTIONS_PORTAL_URL = 'https://customers.gitlab.com'
-
   before_filter :check_presence_of_license
 
   def new
@@ -24,7 +22,7 @@ class TrialsController < ApplicationController
   end
 
   def save_license
-    result = HTTParty.post("#{SUBSCRIPTIONS_PORTAL_URL}/trials", body: params)
+    result = HTTParty.post("#{Gitlab::SUBSCRIPTIONS_URL}/trials", body: params)
 
     if result.ok?
       @license.data = result['license_key']

app/helpers/license_helper.rb

@@ -19,7 +19,7 @@ module LicenseHelper
   def trial_license_message
     return unless signed_in? && current_license&.trial?
 
-    buy_now_link = link_to('Buy now!', 'https://customers.gitlab.com/plans', target: '_blank')
+    buy_now_link = link_to('Buy now!', "#{Gitlab::SUBSCRIPTIONS_URL}/plans", target: '_blank')
     message =
       if current_license.expired?
         if current_user.admin?

app/views/admin/licenses/show.html.haml

 - page_title "License"
 %h3.page-title
   Your License
-  = link_to 'Upload New License', new_admin_license_path, class: "btn btn-new pull-right"
+  - if current_license.trial?
+    = link_to 'Buy License', "#{Gitlab::SUBSCRIPTIONS_URL}/plans", target: '_blank', class: "btn btn-new pull-right"
+    = link_to 'Upload New License', new_admin_license_path, class: "btn pull-right"
+  - else
+    = link_to 'Upload New License', new_admin_license_path, class: "btn btn-new pull-right"
 
 %hr
 
@@ -32,11 +36,13 @@
               Expired:
             - else
               Expires:
-          %strong
-            - if @license.will_expire?
-              = time_ago_with_tooltip @license.expires_at
-            - else
-              Never
+          - if @license.will_expire?
+            %strong= time_ago_with_tooltip(@license.expires_at)
+            - if @license.trial?
+              - remaining_days = (@license.expires_at - Date.today).to_i
+              %span= "(Free trial will expire in #{pluralize(remaining_days, 'day')})"
+          - else
+            %strong Never
 
           - if @license.expired?
             %span.label.label-danger.pull-right

lib/gitlab.rb

@@ -3,6 +3,7 @@ require_dependency 'gitlab/git'
 module Gitlab
   SUBDOMAIN_REGEX = %r{\Ahttps://[a-z0-9]+\.gitlab\.com\z}
   COM_URL = 'https://gitlab.com'.freeze
+  SUBSCRIPTIONS_URL = 'https://customers.gitlab.com'.freeze
 
   def self.com?
     # Check `gl_subdomain?` as well to keep parity with gitlab.com