Poetry on display

I am working with an artist on a future display at our library. He is a regionally known professional artist. He is working on an engraving that makes use of a short poem by a deceased, well-known poet. He has learned that the poem is still under copyright and that the poet’s estate is active, but believes that unless it gets renewed, the poem should be in the public domain by the end of the year. If the exhibition is to be before that time, should he apply for permission to use it? If so, is that likely to be expensive?