A common problem with sink drain lines, bathtub lines, and laundry lines, is soap build-up.
Soaps, especially liquid hand soap, leave fatty deposits within drain lines, and creates a catch point for hair, lint, or anything else that may go down the drain. Drain cleaners on the market, today, are heavy caustics that can damage the pipes, by eating out rust deposits and weakening the pipe, itself.
The best suggestion, to control the build-up within the lines, is to use about a cup of household bleach, pouring it down the open drain monthly, and running hot water for five to ten minutes, afterward. The bleach will soften the greasy build-up and hot water will move it through the pipe. Of course, eventually, hair and lint will get caught, but it will not be as often.
Whatever you do, if bleach does not keep the line open, do NOT pour another drain cleaning product down the line. If the chemicals mix, it can create a chemical reaction and put hazardous gases into your home, or even explode. It is hazardous to you and your family, if you breathe the fumes, and it prohibits anyone from working on the line.