I found soulution to this, I had this problem with our employees as some of them are working outdoors. What I did, since I was the controller of medical supplies, I include in the monthly request 10-15 pcs deodorant, lol
When a patient came into the clinic for treatment with extra problem(body odor/underarm), I gave them 1 pc. and in a nice way I say "don't get me wrong but I think you need to use this after shower" and the next time they buy their own...see how effective? :)