Bandsintown no longer offers the ability to install the Live Shows tab on Facebook Pages.
If you had already installed the Live Shows tab on your Facebook Page previously, it is accessible from the list of tabs at the top of your page when loading it on a desktop computer:
If you reordered the tabs or added new tabs among the first four displayed, the Live Shows tab will be accessible from the More dropdown menu.
Facebook does not allow third-party tabs to be displayed on mobile.
Facebook does not support third-party tabs on its redesigned "New Pages Experience" (more info).