Hey Mehroof,
Thanks for going Pro and using our plugins! I’m sorry you are having this issue with the popup tooltip, let me try to help you out with that.
I looked at your page and the code, and it looks like that the tooltip is missing from the code itself. This could be caused by the theme overriding the calendar templates.
Does the issue still exist when you switch to a default theme like twentysixteen? Please check. If it works fine, then the theme you are using overrides that part.
In this case what you can do is check the template overrides of your theme and adjust those. This can be a simple upgrade (copy the template files from the plugin to the theme to get the latest version) or if the theme does more customizations, then you will need to manually edit / adjust your templates.
These 2 articles should help you get started on the customization:
https://theeventscalendar.com/knowledgebase/themers-guide/
https://theeventscalendar.com/knowledgebase/template-overview/
Let me know what you find out.
Cheers,
Andras