There is nothing to do with the key card immediately. Go back to the museum to find a package waiting for you. You will be leaving Counterfeit Island (temporarily) to travel to another island, for some valuable information.
When he leaves he will leave it on the docks
You'll need it later on to get into Black Widows' Lair.
When you chase him through the streets, he jumps into a boat at the dock and drops his key card. Then you can get it.
with the card on counterfeit you need it for the black widow's ''base"
It will.
you get in the boat and sink
Although you chase him on the scooter, you can't catch him. But he drops the Key Card. Pick it up and go back to the museum, where you have a package waiting.
Towards the end of the island, an assistant of the black widow will be hiding out there. You have to chase him from there to the docks. He gets away, but he drops a key card. From there your quest continues. Hope that helps.
In the clown store
if you want keycard then go to poptropicahelp.net and do island guide
The key card is for later. Return to the museum, where you have a package waiting for you.
its on the edge of the dock