Starting with Minecraft version 1.7.10, all server owners will need to accept Mojang's end user license agreement (EULA) which can be found at account.mojang.com/documents/minecraft_eula. As of Minecraft version 1.9.4, Mojang has begun to block servers which do not adhere to their EULA.
Accepting the EULA
NodePanel will generally prompt you for an acceptance of the EULA when necessary (such as on an initial server startup), however if this is not the case, you will need to manually accept it by editing the eula.txt file and ensure it contains
eula=true. This can be accomplished either via FTP, or NodePanel's File Manager.
For further reading and to ensure you're adhering to Mojang's EULA, we recommend checking out Mojang's blog post regarding server monetization at: mojang.com/2014/06/lets-talk-server-monetisation