Hello Giulia,

Thank you for reaching out and I am happy to help!
I’ve removed the sensitive information because this is a public Forum.
I’ve also sent you an email with all instructions as there is a typo in the license key you shared.
As I mentioned via the W3 Total Cache support channel, enter the license key in Performance>General settings, Licensing sub-box, license field, verify the license with the “verify license button” and save all settings.

W3 Total Cache Pro should be active after these steps!

Thanks!