If you do not use cookies at all on a web-site, you do not have to put up any sign about cookies.
If you use cookies purely for a webshop’s login-functionality, then you don’t have to either.
-Unfortunately, too many people do not know this and we all get spammed with signs and nags. 
Our politicians (in the EU) didn’t know exactly what they were doing and I’d say they killed the joy of web-browsing.