How to limit script activation for users

Hello!
I am using your script on two my sites, one of them is older than the other.
On both sites i am using same javascript code with you plugin (I specified the required categories for code activation in the cat properties tab).
But, there is differense with script activation count in sites. In the old site script is activated only once per user session and it does not matter from what point of site script was activated. You must clear your browser’s cache to activate it again.
But on second newer site, srcipt activates every time then user clicks on specified category.

So, the first case is preferable to me and I would like to know how to configure it on my second site.

Thanks!