Review your current photos.
To display the badge, simply swipe right on the Festival Mode card for the event when it pops up in your card stack.
If you want to see them all, you have to upgrade for a membership.
There is also a space where you can swipe through only photo-verified profiles.
Tinder rolled out Recently Active status also to the Discovery screen for Gold subscribers, so you can also see profiles that have been active on Tinder in the last 24 hours whether they liked you or not yet.
Coins can be purchased inside the app, then exchanged for ala carte premium perks like Super Likes and Boosts.