The ESB (End of Service Benefit) payment is covered within Qatari labour law. I believe that if it is not covered within the contract that it is compulsory by default. If it is mentioned in the contract that you don't receive ESB then that is applied.
For lower level staff in some organisations the amount is lower than for higher level staff.
Within QP and after 5 years service the amounts for Senior Staff used to be higher than the legal requirement at:
1 month's terminal basic salary for the first 5 years of service.
1 and a half months basic terminal salary for 5 to 10 years service
2 months basic terminal salary for service in excess of 10 years.

After the changes introduced in 1997, ESB within QP was reduced to one month per year of service for a maximum of 10 years. I don't know if it's paid annually at current salary or at terminal basic salary if it is allowed to accrue until termination.