All the sites on which I have the premium installed were hosed after the upgrade to 2.12.0 of the free plugin.
Both, backend (admin) and frontend were not accessible. This is the error shown:
Fatal error: Undefined class constant 'pt' in /<site-path>/wp-content/plugins/testimonials-widget-premium/testimonials-widget-premium.php on line 799
Used FTP to remove the premium plugin, everything is up again, except for one site. With the premium installed on that site I get a memory error:
Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 523800 bytes) in /<site-path>/wp-content/plugins/testimonials-widget/lib/class-settings-testimonials-widget.php on line 491
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