I have imported a site into my local Kentico CMS Desk. The export had Media Library and physical files in it. But when I log into my local CMS Desk I do not get the option of Media Library in CMS Desk - Tools option. I am logged in as Global Administrator both during export and import and I have permission on the Media Library module to Create, Modify and Destroy in CMS Desk. The UI Personalization for this user displays the checkbox for Media Library - Add new library.
I have also checked Developments - Module setting and it confirms that the media library is available for my site.
My hotfix patch on both sides is 42.