“因为你曾经出现给我美好的回忆”的英语

Because you showed up and gave/brought me all those beautiful memories.
这边你出现和带来美好回忆都强调了动作.
Because of your existence and those beautiful memories you brought me.
这边则是以名词形式并列.

because once your appearance gives me a pretty memory

Because you were there and gave me wonderful memories.