If After Effects CC 2014 asks for a serial number, it is often a sign of a technical error rather than a missing key: Incorrect Hosts File:

Always opt for legal and legitimate ways to obtain software. Not only does this support the developers, but it also ensures you're working with secure and up-to-date technology. If you're having trouble finding your serial number or need assistance with purchasing, reaching out to Adobe directly or through authorized channels is the best course of action.

If you're having trouble with your serial number or are looking for alternatives to purchase Adobe After Effects, consider visiting the official Adobe website for more information on current licensing options and support resources.