The VT-03 when properly conditioned will last up to 65 hours.
Excursion-Trac™ devices have a rolling memory structure that stores the most recent 525,600 temperature observations (it will over-write data). Memory-Loc™ devices have a permanent memory structure that stores 1,051,200 temperature observations (it will NOT over-write data and cannot be cleared when full).
Your freezer must be below at least -15°C. -25°C or below is recommended to get the panels solid (for maximum hold time). The colder the storage environment, the less time is needed to condition the panels for use.