The famous phrase memento mori (the subject of this question) means something like "remember that you will die, remember you are mortal". But this use of the infinitive seems odd.
Memini is often used with an infinitive, but (as per L&S) these uses fall into two classes: (a) "remember that (a thing happened)", and (b) "remember to do something, be sure to... do not fail to...". Memento mori falls into neither class. It's certainly not (a), but it isn't really (b) either -- the meaning isn't "Don't forget to die!". For the sense of "remember that something will happen", one would have expected an accusative with future infinitive: Memento te moriturum esse.
Is this just a quirk of this single phrase? But if so, how would Latin speakers have known to interpret it correctly? It seems like there ought to be comparable uses of the infinitive, either with memini or with other verbs. Are there such comparable uses?