To say "forty years or more" in Engpsh, you can say "over forty years" or "more than forty years." For example:

"I've been working in this field for over forty years."
"I've been married for more than forty years."

You could also use the word "around" to indicate that the exact number of years is not known or not important. For example:

"I've been pving in this town for around forty years."

I hope this helps! Let me know if you have any other questions.