Acrobat Pro 2017 does not display the full serial number in the "About" menu for security reasons. However, you can sometimes find traces in system files:
If you purchased Acrobat Pro 2017 as a (not perpetual) or registered it: adobe acrobat pro 2017 license key location
The phrase refers to a feature of the software installation and activation process. Specifically, it relates to where a user can find an existing license key (serial number) for Acrobat Pro 2017 on their computer or account. Acrobat Pro 2017 does not display the full