Last Friday of every month - which means sometimes you have to make four weeks pay last for five weeks on months where the friday is the last day of the month. There is usually about 3-4 five week months in a year (bonus when you get five weeks pay for the following four weeks though!).
Monthly and weekly
Its a little strange, rather than the pay being worked out to provide 12 equal months of pay, you will receive some months consisting of 4 weeks pay and some at 5 weeks pay, can make your budgeting a little hap hazard.
Monthly, the last Friday of every month.