Wayne
This is only partially true.
There is a "Serial Number", else you couldn't download the software from FileConnect:
https://fileconnect.symantec.com/licenselogin.jsp?localeStr=en_US
It's even in the license file (SLF):
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<licenses xmlns="https://licensing.symantec.com">
<license signature="skldgsljdgjkslrgksjrglksödrjgsölergjserl gsjerlögsjöer">
<license_format>1</license_format>
<fulfillment_id>1234567.8</fulfillment_id>
<serial_id>9908493.7</serial_id>
<serial_number>M5738574654</serial_number>
<product_name>Symantec Enterprise Vault PST Migrator 7.0</product_name>
<sign_date>2007-03-27</sign_date>
<key>
<name>EVPSTM</name>
<version>1.0</version>
</key>
</license>
</licenses>
So, yes, EV does not use the Serial Number directly, but you need it to get the software nowadays... ;)
Cheers