As it stands Belgium international Lukaku, who has scored 12 goals for the Baggies this season, will return to his parent club Chelsea in the summer.
However, fellow striker Long believes that the 19-year-old would benefit from spending another year at The Hawthorns.
"Rom is still young. You look at him and can't believe he is 19 or 20. He has a lot of learning to do but he wants to learn, is relishing the challenge here and it is good to play alongside him," said the Irish international.
"They've got plenty of options at Chelsea and I think he likes it here. He likes playing for the manager, he likes the lads and he finds it fun coming to training every day.
"Hopefully we can get him back next season and keep him going the way he is going."
Chelsea paid Anderlecht £18m for Lukaku's services in 2011.