Key of Bb

5 chord vamp entire song, however the guitar is playing a 5 - 4 loop. Also a great tune to practice 5 - 4  major - major triad pairs. 

Key of G

Intro Chord is based on a D7 type chord, D-C-B-A (1-b7-6-5). D on the A string, C on the G string, open B string, A on the high E.

Verse:
5 - 5 - 2 - 2
4 - 6 - Riff

Chorus:
4 - 6 - 5 - 5

Key of Gb

Verse:
5 - 4 - 1 - 5 (Bass riff plays a normal 4th over that 4 chord)

Chorus:
2(maj) - 4 - 5 - 5 (Guitar plays a normal 4th over that 4 chord)

Solo section and ending is written around the 6 chord 

G7 - D7 for the entire tune

As there is no key with two dominant chords, this song is technically not in a single key. However it is doing what thousands of "blues" style tunes do, which is play normal progressions but make everything dominant. So you could look at it as the key of G, 1 - 5 but both are dominant. 

Good backing track to practice dominant ideas, although the song starts to become a bit annoying after a while. 

Key of G

5 - 5 - 4 - 1

Don't even need to hear the progression to get the sound. The melody alone gives you everything you need, as she is singing blatant 5 chord before the music even comes in.