The verb meminisse is irregular. It has only the active perfect system (memini, meministi, meminit…) and the imperatives memento and mementote. These imperatives are future imperatives by form, and I would like to know if they are future by meaning, too.
Regular verbs have present and future imperatives (eg. ama(te) and amato(te)) and there is a semantic difference between the two. The verb meminisse has only one type of imperative, which is of future form. Is memento(te) semantically present or future imperative? Or perhaps it is both or we cannot tell. I do not recall ever seeing a discussion about this.
The imperative memento came up in two questions recently: Negative Future Imperatives and Parallels for the infinitive in “memento mori”?.