Version 5.5 was/is not part of the Cloud, so you could not have subscribed to that version
You install version 5.5 on a 2nd computer exactly the same way you did the 1st time... put the disc in the drive and enter your serial number when asked
Does your serial number show on your account page?
https://www.adobe.com/account.html for serial numbers on your Adobe page... or
Lost serial # http://helpx.adobe.com/x-productkb/global/find-serial-number.html