Should I enable Mobile Detect on my website?
This fully depends on what is installed on your website or what you are trying to achieve. For instance, if you use another LoginSecure extension that needs Mobile Detect to be active then this extension will tell you this in the form of a warning on the published page.
If you would like to use the mobile detect functions in your own PHP code then it is also recommended to have it active ;-).
Otherwise, you can switch it off. And do not worry if you install in the future an extension from LoginSecure that requires the files to be active then this extension will inform you about this.