Hi there,
Sounds a bit privacy confusing to walk around constantly recording, but it's a memory of your life... It might be strange to me, but I might have part of a solution for you.
You could potentially set a "Profile" that triggers with "Call ~ any (from any number)" - which causes (As an "Enter Task") the app Life Memory to be cleared from running apps or be force closed.
Then the app has to be restarted when the Call is ended (run an "Exit Task"). That might be more convoluted. If Life Memory provided an integration with Tasker, you'd be able to start and call the recording probably. Does Life Memory just start recording once it opens? You could make the Exit Task run an application launch for Life Memory, it might start up and continue recording.
Otherwise, it might pop up after a call if you ask it to open the app, and you could tap "resume" or whatever the UI says. You could use AutoInput by the maker of Tasker to tap the screen for you, but that might be more difficult for a novice, and can be unreliable. Tapping "resume" in app would actually be best bet for being sure it's working, and Tasker at a basic level should be able to close and open the app at the right times. (I'm less sure about WhatsApp calls in a Tasker Profile. The "call" profile is on the system, not third party like WhatsApp)
Good luck!