[RPG] If a spellcaster forgets Find Familiar, can they keep the familiar


Some spellcasting classes (e.g. Sorcerer or Eldritch Knight) have the ability to 'forget' one of their known spells and swap it for another when they level. If they knew Find Familiar, and used it to obtain a familiar, can they swap out the Find Familiar spell but keep the familiar?

Obviously they would not be able to change its form, or replace it on death, since either of these abilities requires casting the spell again. But can they keep the familiar with all its abilities?

Best Answer

Mechanically, I believe so:

Find familiar, on page 240 of the PHB, has duration "Instantaneous".

From page 203:

The spell harms, heals, creates, or alters a creature or an object in a way that can’t be dispelled, because its magic exists only for an instant.

As a result, there is no need for you to keep up concentration, or even still know the spell to maintain the effects of an instantaneous spell, in the same way that if you cast fireball and later relearn it, your enemies don't get unburnt.

Flavorwise, I'd highly suggest you keep it, but mechanically there is nothing stopping the scenario you describe.