Who owns this sample?
The very first condition is to properly label every sample. The minimum information is "name of sample", "owner", and "date". Depending on the size of the vessel, you might add further information e.g. "concentration", "volume" or "source". The labeling should be done with a black pen (maximum contrast) and proper handwriting for easy reading. Even better are printed stickers.
Any writing or sticker on the vessel should be secured with transparent sticky tape.
Remember, vessels which miss a proper label will end up in the autoclave.
How to document?
The ancient way is paper-based. Every freezer box has its own spreadsheet with up to 100 lines.
The pro’s are the ease-of-use, the location of the list at the freezer and the time-saving when adding a sample by pen. As a drawback, it is limited to very low numbers of samples due to growing lack of clarity, you have no backup of those mostly handwritten documents, and the readability depends on the author.