I don't know which plugins you use on site, but according to label on button, it's definitely set by one of affiliate plugins or by customizations on your site. 

page is cached - but I have flushed everything and it is not working

I am able to edit the button text of the other pages of my website and I do not understand why this one is not responding.

which plugins do you mean? 

Hi there,

I am not able to edit the text of my affiliation link button

https://nnhotempo.it/cucina/macchina-caffe/cecotec-power-matic-ccino-vaporissima/

as you can see I am correctly editing the button but the change does not reflecting in the above page: https://imgur.com/a/0fD29ca

Thank you for help