Question about possible abusing your theme usage

I have question about you theme – recently i got 2 clients from one agency that used your theme. Both had idnetical version of yout theme with blocked wp and theme updates. Asked them for a key that was used to activate client sites and them refused to give it. In css i found

/*
Theme Name: Enfold
Description: A superflexible and responsive Business Theme by Entera
Version: 3.8.5
Author: Kriesi
Author URI: http://www.entera.pl
License: Entera Split Licence
License URI: –
Theme URI: http://www.entera.pl

– modded base css file with agency adress. I checked their portfolio and found over 40 sites with exactly the same setup wp/ theme version. I know that themeforest have normal and developer licence but this usage seems to be a piracy