I already answered this: via cpconfig (a CLI command).
There is a menu option called Check Point CoreXL.
Select it and follow the menu prompts to ensure it is enabled and with the correct number of firewall (worker) instances, which should be 3 to start with.
Now you may be able to do this BEFORE you reboot the gateway AFTER applying the license--not 100% sure about that.
And you may need to do additional tuning later, which is covered in the SKs I pointed to
In either case, it all starts with cpconfig.
The SKs I pointed at can be used to further tune/troubleshoot later, but given you only have 4 cores, your options for tuning are fairly limited.