Rosemarry, the FET I did last cycle was a natural FET. I still used progesterone pessaries after transfer, but I don't think they're essential (kind of just an extra boost, which I was happy to have because I think my natural progesterone levels may be low lately). You could always get your progesterone level tested at 7dpo to see if it's high enough and only use the pessaries if your level is low.