Keeping the tempo or beat of a song is vital for all musicians; therefore, drummers are no exception. Although many drummers count-off tempos from memory, more and more drum players use a metronome to help them with that and enjoy great accuracy.
The use of such a device is of great help especially when it comes to gigs. Even if you know a song by heart, a live performance is demanding and challenging. You have the lights, the audience, and the rest of the band you have to stay in sync with.
Many professional drummers use a metronome and not just when practicing but also when performing on stage. For example, Steve Gadd has made use of such a device on stage and the list could go on. Moreover, many modern bands have added in-ear monitoring systems to their stage equipment to keep the tempo with greater ease.