The previous version of Adsense interface used to show its users the last successful login time of the account. However this has been removed in the new upgraded version. Still if you are very much interested to check it out, here is the trick.
Step 1: Login to your Adsense account and stay there.
Step 2: Open the source code of the page by right clicking on your browser. The actual command depends on the browser you are using. In IE it is View source, for Google Chrome and Mozilla Firefox it is View page source, for Opera it is simply Source.
Step 3: The code may be very cluttered, so you have to put some extra effort to find the information we are looking for. Scroll down the code and look for these lines in <head> section. Or make use of Ctlr+F shortcut to find out the string.
<meta name="gwt:property" content="firstname.lastname@example.org"> <meta name="gwt:property" content="syn.lastLogin=Last Login: 23 hours ago">
The meta tag shows the time when I had last visit to the website. May be its not very useful to check it out every time, but yes, the information do exist if you want trace it.