No-one seems to have answered this. So I shall try to do it even though it's not a chip I've used.
Looking at the data sheet, I see that BlueNRG-2 (note spelling) has 256K of FLASH, writeable in 1 or 4 32-bit words and erasable in 2kByte pages.
It's not easy to use FLASH as non-volatile storage because your program has to manage the fact that writing only changes bits from 1 to 0, and you need to erase to return them to 1. And you need to allow for the possibility of loss-of-power during the erase. But ST do have application notes on how this might be done e.g. AN4894 for stm32l4.
Now you might have looked into this further as to why this is unusable in your case. In which case please explain why.
Hope this helps,
Danish
