Don't forget you have a family,people who love you and the promise you made.（77字符）
语法严谨最精简也必须是如上的句子,将那 "三点" 并列（以逗号和 and 连接).
但仍然没办法满足 68 个字符的要求,除非
1) 将“你的承诺” 简化
2) 将“不要忘记” 改为 “记住” （反正一样都是祈使句型）
Remember you have a family,people who love you and the promise you made.（73字符）
Don't forget you have a family,people who love you and your promise.（69字符）
Remember you have a family,people who love you and your promise.（65字符）