The disk is redundant as you can download LR from Adobe, and finish the installation with the supplied serial number. Just make sure you download the perpetual/ standalone version, NOT the CC one.
You can download LR for your Mac from here:
The best thing is to get the latest version of whatever version series (LR4 or LR5) your disc is.
In other words, if the disc is LR4 then download and install LR 4.4.1. If the disc is LR5 then download and install LR 5.7.1.
For this to be useful beyond the 30-day trial, the disc should have also included a serial number or its precursor, a redemption code, along with instructions for how to redeem it for a serial number.