Epson inkjet printers use a self-cleaning cycle. During this process, a small amount of ink is flushed through the printhead into a absorbent pad inside the machine. Over months of use, this pad fills up. Epson designs their printers to count every drop of waste ink. Once the counter reaches a preset maximum (usually around 15,000-30,000 cleaning cycles), the printer triggers a permanent lock.
Professional keys are sold by third-party developers. These are generated per transaction and are the only way to achieve a full 100% reset of the internal counter. Critical Safety Warnings Epson Wic Reset Key List