Non-volatile counter (MAXII)?

It doesn't work that way. As one point, UFM has to be erased before rewriting, as another point, it has a specification of 100 erase/reprogram cycles.

It may work by writing single flash bits from '1' (erased state) to '0', having each bit representing the same amount of time. With 8k bits, this would allow a very coarse resolution only. However, by MAX II specification, only 2 write accesses per word between erases are allowed, rather than 16, as required by the suggested programming scheme. But it may work anyway, you can try.

UFM works well for applications like storing serial numbers or calibration data.