Go here to redeem(make an account & link gaming platforms if not already): https://shift.gearboxsoftware.com/rewards
Codes:
XB1: CTWTJ-FZSFW-FHXFH-WRJBT-3K5WF
PC: 5BW3J-XC99J-3FJ6K-3TBJJ-BJK9S
PS4: 5BKTT-RH399-6TK9C-ZTCJT-HZ65C
Add them individually for each platform.
The codes are active until 02.12.2019.