This key will enable a single Raspberry Pi (excluding Raspberry Pi 4 and Raspberry Pi 5) to decode MPEG-2 video in hardware. You will need to provide your device's internal 16-digit serial number as part of your order. Your serial number is not the number printed on your board.
To find your serial number on Raspberry Pi OS, type cat /proc/cpuinfo at the command line as shown below:
pi@raspberrypi:~$ cat /proc/cpuinfo
Processor : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS : 697.95
Features : swp half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xb76
CPU revision : 7
Hardware : BCM2708
Revision : 1000002
Serial : 000000000000000d
