The Stella Medal (official name is just Stella Vyctory) is a badge that Ingress players can unlock in their scanners.
It's description says the following
"Aided Endgame researcher Stella V. and chose a Line."
This medal was given in some Ingress events during the Persepolis anomaly series.
It was also promised to players of Endgame: Ancient Truth that the first 1000 of the leaderboard would obtain one.
On the 20th of July Robyn Sanning started contacting players that were in the top 1000 to give them a code that could be used to redeem a badge in the scanner. This was done until 31 of July.
After this date players that were on the top 1000 and had not received their medal could contact the Robyn via the mail insanningty@gmail.com to obtain theirs.