If not, the best clue is to look at the final chord. That chord (and often the final note of the melody, also) will usually name the key.

1. MELODY
&
PITCH NAMES

2. MELODY- A melody also tune, voice or line, is a
linear succession of musical tones that the listener
perceives as a single entity. In its most literal sense, a
melody is a combination of pitch and rhythm, while more
figuratively, the term can include successions of other
musical elements such as tonal color. It is the foreground
to the background accompaniment. A line or part need
not be a foreground melody.