It stopped working for me a couple of days ago. Every time I try translating anything i get "Error: Service usage limit reached. Please wait a while and try again". I was not doing anything weird with it, I'm not a heavy user, just translating one or two things every couple of days. I have been using it for years with no problems and I really liked this addon, but right now it's unusable for me because of this.

Edit: Somehow it fixed itself.