If a person has gained 10 pounds of muscle and mass by taking pro hormones will this weight be lost if the product is discontinued?

A teacher once said in nursing school that if you use hormones or other muscles building "pill" techniques then muscle will not be lost if you stop taking the "pill" but it will be harder for you to work out and continue building muscle unless you work twice as hard at it because the hormone makes it easier for you to gain muscle.

maybe alot of the 10 pounds is probably water weight