Presumably there is some implied distinction between episodic memory and procedural memory in particular. Otherwise one wouldn't be able to coherently reason or walk even.

But if only episodic memory is erased then one could recourse to procedural memory to prove oneself. For example the performance of a speicific trick could be used. If you relay the message to yourself via a video of yourself performing the trick this allows for easy comparison.

This brings the next class of approach: Use videos of yourself which you can compare for biometric features.