The Voice Memos app, unfortunately, does not have an Open-In app option. Not sure why – leave it to Apple to not implement their own stuff. If you are trying to get tracks from Voice Memos into Anytune, you will have to send it into an email first, and then from the email you can press and hold on the attachment and Open-In to Anytune.
If your plan is to ultimately use the tracks with Anytune, you could always use the built-in recording option in Anytune as an alternative. Tap the green + button at the bottom of the Tunes list and select Record.