Dit staat in hun statement:
" We request you retain the full copyright notice below including the link to
www.phpbb.com.This not only gives respect to the large amount of time given freely by the developers but also helps build interest, traffic and use of phpBB 2.0. If you cannot (for good reason) retain the full copyright we request you at least leave in place the Powered by phpBB line, with phpBB linked to
www.phpbb.com. If you refuse to include even this then support on our forums may be affected. "
Het is dus niet verplicht - het zou enkel een probleem kunnen opleveren als je support nodig hebt.