I just pollinated a Frankenstein downstairs with pollen from this gentleman about a week and a half ago… already seeing seeds starting to form. The pollen’s been in the fridge for 2+ years now, apparently.
@PhilCuisine says he’s gotten seeds from pollen stored in the freezer for 15 years. Dunno if the fridge works quite that well, but I can personally testify that it certainly lasts a while.