For which product you are looking for a license key? As per the given email I couldn't find any serial number registered to this account.
However, there is a subscription registered for the Adobe Export PDF. If you are referring to the Export PDF then it doesn't require any serial number to activate it.
Adobe Export PDF is an online service that you can access online via https://cloud.acrobat.com/exportpdf or you can install the Adobe Reader DC desktop application through- Adobe Acrobat Reader DC Install for all versions
To activate the service of Export PDF, you need to "Sign In" using your Adobe ID under which you have subscribed for Export PDF.
Let us know if you are referring to some other product that you bought.