persistence

You've got to admire her persistence. She's asked him out every day for a month even though she keeps turning him down.

Once written to a disk file, the data has persistence: it will still be there tomorrow when we run the next program.

The persistence of the number 39 under the operation of multiplying the digits of the number is three, because 3x9 = 27, 2x7 = 14, and 1x4 = 4, and no further iterations will change the number again.