# These days were to be remembered and celebrated

"The Jews were to remember and celebrate these days" 

# These days of Purim should never fail from among the Jews

"The Jews should never fail to celebrate these days of Purim"

# their memory should never come to an end for their descendants

"the memory of those days should never come to an end for the descendants of the Jews" or "the descendants of the Jews should never forget those days"