There is always a way to tell if you have galactic memory. For instance if you feel like maybe you are other-kin, an old soul or you just don't fit in, and you've grown past the typical stage of a teen-agers life of not belonging to anything. You could even find a group that you fit with and you still feel like you do not fit. The more the world turns, you feel yourself grow even more distant form it. You are also never satisfied. You have everything you need or desire and you are left wanting. You feel empty. Not from depression or loss but you do not feel complete no matter what you do.
These are all signs of having a star soul, and being from galactic space.
Not to mention the biggest one, having visions and dreams of alien worlds, places you
just know that are not on Earth, Stars and Ships in fleets and battle. Plasma like laser weapons, Missions to want to try and hurt earth or stop an Earth style mission, space and galaxies, ships and fleets, seeing yourself in another type of dress and or skin color not from earth. This is a very distinct feeling, and you feel a tightness in your gut where your stomach chakra is, this chakra is one of nurturing and growth but also one of deep instinctual knowledges.
The difference between Imagination and daydreams and past life memories is, normally in daydreams no body dies. There are not terrible wars and terrible diseases, there are no awful people coming to invade, and take you over and fuck up your dna and genetic structures.
..Unless your like George Lucas and knew you could make some serious bank off it. j/k hehehe *wink*