Could a person relapse from anorexia 8 years later?

Unfortunately, yes. Anorexia, along with other eating disorders, are not problems you can have "part way." It can start slowly as a result of increased stress, anger, loneliness and other emotions and this is the chance to catch it. Seeing a therapist or a doctor that helped in the past can support your putting on the brakes. Without this intervention, it is very likely that it will escalate.