Spray Tans are not always permanent but if someone has a certain skin cell type then the spray tan may become permanent or semi permanent.
Most times the spray tan will wear off your skin and body within 6 months to a year after having the spray tan depending on your skin cells.
However some people who have spray tans have the spray tan start fading away within 10 to 15 days because the spray tan is only as long lasting as a persons skin cells.
So while sometimes the spray tans may become permanent in some people they usually are only short term lasting spray tans and usually start disappearing within 10 to 15 days.