Just today I purchased the plugin Leaderheads. When I put the plugin in my server files and restarted my server I get this message in console:

02.03 21:59:30 [Server] INFO at me.robin.leaderheads.LeaderHeads.onEnable(LeaderHeads.java) ~[?:?]
02.03 21:59:30 [Server] INFO at me.robin.leaderheads.LeaderHeads.loadConfig0(LeaderHeads.java) ~[?:?]
02.03 21:59:30 [Server] INFO java.lang.RuntimeException: Access to this plugin has been disabled due to piracy! Please contact SpigotMC!
02.03 21:59:30 [Server] ERROR Error occurred while enabling LeaderHeads v10.3 (Is it up to date?)
02.03 21:59:30 [Server] INFO [LeaderHeads] Enabling LeaderHeads v10.3

Can you please help me figure out why it is disabling it due to piracy when I just purchased the plugin?