The time limited version will only be generated if you do not have a Nios II license. Since you are using the eval. version, you are in this situation. You "might" be able to get out of it by programming your "time limited" SOF to the board, manually, using Quartus II, _keeping_ the little OCP "warning" window open, and then trying to run the Nios II Flash Programmer.
Or, you could just purchase a license and avoid the hassle. :-)
In the meantime, you could try to run the memtest software example on your hardware to verify that everything functions. You'll hit the OCP/"time limited" stuff here (you _must_ keep the little "warning" popup open), as well.
Cheers,
- slacker