You must provide Adobe Customer Service with proof of purchase in order to resolve a number of issues (for example, to obtain a new serial number or show eligibility to qualify for a post-announce upgrade).
The Adobe Customer Service agent who handles your issue will tell you where to fax your proof of purchase.
Legitimate proof of purchase qualifications
Adobe accepts the following items as legitimate proof of purchase:
Note: Purchases from private individuals, online auction sites, or software clearance centers do not qualify as legitimate purchases.