Download the Altair License Manager from Marketplace on Altair One. The License Manager Tab would be accessible for all the applications for which you have a license.
Save the executable in a local drive on the Server on which it is to be installed.
Before installing ALM15.2.0, the current version of the Altair License Server should first be uninstalled, and all the directories are to be deleted.
It is suggested to have a backup of the altair-serv.cfg, alus.conf files, data, and logs folder from the licensing folder, before uninstalling the current version of ALM. A backup will usually be taken by default when uninstalling the older ALM.
Once done, refer to the video showing the steps to install Altair License Manager.
Please Note: Please make sure there is only one *.dat or *.lic (license file) in the installation directory.