Option 1: Get KMS licenses in place for Win7 from Microsoft. -by far the easiest.
Option 2: Use SYSPREP instead of QuickPrep
Option 3: Add 1 at a time and activate the link clones manually b4 customizing finishes - Pain in the rear. Or be creative if it's your test env.
Option 4: Hack the reg key that supossedly has composer activate. Below is the info:
HKLMsystem/CurrentControlSet/services/vmware-viewcomposer-ga/SkipLicenseActivation to '1'.
Of course the Win7 desktop will be in evaluation-mode until the eval-period expires but can be useful in a temporary setup or POC,