The Lascar EL-USB series
The Lascar EL-USB-series are data loggers which you simply configure then place inside the fridge, freezer or chilly bin and they quietly go about their business of measuring and logging temperature.
With the very easy to use software supplied, you can configure the data logger to log the temperature every ten minutes for a very long time. Then, for example each week, you remove the logger, plug it into your computers USB port and download the data for review and archiving. The it is available for later audit etc..