Credits are the currency for StarMade, accepted at all shops. Credits are used to buy anything in a shop (so long as it is in stock) and are earned/gained when you sell material at shops or are given it by a player(s). Each player starts out with 25,000 credits. This value can be changed in the server.cfg file ("STARTING_CREDITS"), along with the percentage of credits lost by death ("PLAYER_DEATH_CREDIT_PUNISHMENT").
The amount of credits a player has is displayed at the upper left side.