In all but the most extraordinary of circumstances, the destruction of memories is cost-prohibitive. It is for this reason that The River Lethe exists, as a means of discarding memories which are confiscated. The obvious drawback to keeping forbidden memories intact is that it is possible for other to retrieve them by merely drinking from The River Lethe. It goes without saying that there are countermeasures in place to ensure that this cannot be done without proper authorization. The waters of The River Lethe are cursed, such that no cup can contain them. This also applies to glasses, chalices, goblets, and any implement which might be used to contain water, regardless of whether or not that is its intended purpose. It follows that, if one wishes to drink from the river, they must drink from it directly. (To do so is to receive The Kiss of Death –Clotho) Any who do so, be they mortal, God, or otherwise, are stricken by an irresistible thirst. This compels them to keep drinking, even as they are overwhelmed by a torrent of paradoxes. False secrets, which contradict the truth, are regularly planted into The River Lethe, so that any attempted offenders cannot distinguish what is from what is not. This continues until their very being is overwritten, and all that remains is a shell, filled with memories. This shell petrifies into a fountain, which slowly returns all the stolen memories to The River Lethe, where they belong. (These fountains ensure that those who gaze upon The River of Oblivion will never forget the price paid by those who cross The Moirai –Chloe)
NOTE: this is by no means an exhaustive list of the countermeasures put in place to ensure that information discarded into The River Lethe remains classified. Consider this a warning: If you somehow manage to circumvent the security system described, you will be caught by a different one, and you will suffer in ways that you are incapable of imagining. It is left to you to decide whether or not the previous statement is vacuously true.