"He looked so good, so healthy," Webb, the co-founder of Project Limelight Society, a Vancouver charity close to the actor's heart, tells PEOPLE. "I hadn't seen him look that good in a long time."
Joined by Monteith's manager Elena Kirschner, the trio dined at East of Main, a restaurant that supports the organization. "We ate a lot of food," recalls Webb, noting no one drank alcohol. "We drank the rhubarb lemonade."
Monteith initiated the dinner, telling Webb he wanted to get more involved the non-profit arts program for children that he had supported since its 2011 launch.
"I told him, 'I remember everything we talked about when we first talked about this project. Now it's happening.' His face just lit up. He was in great spirits."
Two days later, on Saturday, the 31-year-old Glee star's body was discovered in his hotel room. No cause of death has been determined but police have ruled out foul play.
For more information or to make donation in Monteith's memory go to Project Limelight Society.