Since; from a certain point in time up to now or thereafter—used to indicate continuity from that time.
大学を卒業して以来、海外に住んでいる。
Since graduating from university, I have been living abroad.
その事故以来、彼は慎重になった。
Since that accident, he has become more cautious.
初めて会った日以来、連絡を取り合っている。
We have kept in touch since the day we first met.