"I unpacked a Probe Droid from a crate, but it disappeared.""I got a Probe Droid from a Cartel Pack, but now it's missing.""I had a Probe Droid companion, but it vanished after I died.""My Probe Droid disappeared after I changed planets."

if you "used" it and unlocked it on your character it should appear in your pets tabPress P to open abilities windowPress the tab and choose petsIt should be listed there with any other pet you have unlocked on this character