Thank you for your quick answer
I looked the page you gave me and empty http://my.maxthon.com/mydevice.htmlIn Device Management page I can see my PC's but I cannot see any history (My latest backup date is 10 May 2014)
"It looks that I can go back forever, but unfortunately I delete my history every now and then so i can't tell you how long maxthon keeps it."
In your online history, you can go back forever and you cannot see your local history because you delete your history every month. Did I understand correctly?