A: Hi favre.arnaud,
That's a great question, folks who purchase the long-term deal from https://appsumo.com/products/ewww-image-optimizer/ can get unlimited sites and extra bandwidth with any of our monthly add-on plans: https://ewww.io/appsumo-addons/
These plans are discounted further than our normal upgrades, AND exclusive to Sumo-lings.

Happy Optimizing!
Shane