On the LWS site (https://licensing.adobe.com).
According to me the best option : you can search via approx dates when it was ordered to arrive at the Order number and download the license certificate.
Secondly if the License certificate you require is for the serial keys .. and if you are a CLP customer.. the license key remains the same for all Web Premium CS5.5 ordered by you or your organisation.
Hope this helps.
