So, let's say an international secret research institute is trying to prepare for if/when the worst happens and some individual happens upon some bit of information or stumbles into a location that reveals the existence of the institute to them. They really need to get them out of the picture before they let someone in the public know exactly what it is the institute is doing. As long as there aren't too many people involved with this lapse in information (which for our purposes, there aren't), the fix shouldn't theoretically be that bad. They could have said person conveniently disappear and never return, but you can only pull that stunt so many times before the public notices or the government of the area (which knows the institute exists and generally is cooperative with it) steps in and interferes. Fortunately for the institute, they've developed a very specific type of drug that (as long as you get the proper dosage in a person within just under a day of their encounter that created this situation) will theoretically do the trick in terms of getting rid of any real memory of their encounter. So, the question here is this; is this really the most feasible way to deal with this person (drug them and send them on their merry way)?
I feel like paying them off only goes so far if you're really adamant on keeping the organization as much of a secret as possible, and keeping the staff completely quiet would be a hard enough job as it is without someone running around with the information that's only keeping their mouth shut for now because you payed or blackmailed them. If anyone can think of alternate solutions to these types of small information breaches, feel free to list them!