Method for estimating a risk of relapse of addictive behavior of an individual, said addictive behavior being related to exposure to an addictive stimulus, said method comprising: At multiple points in time, repeatedly • requesting, by a central server unit, said individual to do at least one of: ∘ conducting a measurement of said individual's exposure to said stimulus; ∘ answering a questionnaire provided in a measurement device; • performing at least one of: ∘ measuring, with said measurement device, said individual's exposure to said stimulus; ∘ collecting, with said measurement device, said individual's questionnaire answers; • transmitting a result from said stimulus exposure measurement, if performed, and said questionnaire answers, if collected, from said measurement device to said central server unit; • storing said result in said central server unit; • upon said central server unit receiving said result, said central server unit estimating a risk of relapse based on a combination of the received result and historic results, and at least one of the following: ∘ time of day when measuring said individual's exposure to said stimulus; ∘ day of week when measuring said individual's exposure to said stimulus; ∘ result of previous measurement of said individual's exposure to said stimulus; ∘ elapsed time since previous measurement of said individual's exposure to said stimulus; ∘ number of historic measurements of said individual's exposure to said stimulus that have been missed; • determining, by said central server unit, a next point in time for requesting said individual to do at least one of conducting a measurement of said individual's exposure to said stimulus and answering a questionnaire, based on said estimated risk, wherein the next point in time is determined so as to collect a time-line of stimuli exposure data that reveals onset patterns, frequency, duration and intensity of stimuli exposure; and • if said estimated risk is greater than a predefined level, transmitting, from said central server unit, a message to a third party, wherein said third party is at least one of: ∘ a health care provider; ∘ a family member or close relative; ∘ an employer; ∘ a law enforcement organization; and ∘ a governmental institution. • requesting, by a central server unit, said individual to do at least one of: ∘ conducting a measurement of said individual's exposure to said stimulus; ∘ answering a questionnaire provided in a measurement device; ∘ conducting a measurement of said individual's exposure to said stimulus; ∘ answering a questionnaire provided in a measurement device; • performing at least one of: ∘ measuring, with said measurement device, said individual's exposure to said stimulus; ∘ collecting, with said measurement device, said individual's questionnaire answers; ∘ measuring, with said measurement device, said individual's exposure to said stimulus; ∘ collecting, with said measurement device, said individual's questionnaire answers; • transmitting a result from said stimulus exposure measurement, if performed, and said questionnaire answers, if collected, from said measurement device to said central server unit; • storing said result in said central server unit; • upon said central server unit receiving said result, said central server unit estimating a risk of relapse based on a combination of the received result and historic results, and at least one of the following: ∘ time of day when measuring said individual's exposure to said stimulus; ∘ day of week when measuring said individual's exposure to said stimulus; ∘ result of previous measurement of said individual's exposure to said stimulus; ∘ elapsed time since previous measurement of said individual's exposure to said stimulus; ∘ number of historic measurements of said individual's exposure to said stimulus that have been missed; ∘ time of day when measuring said individual's exposure to said stimulus; ∘ day of week when measuring said individual's exposure to said stimulus; ∘ result of previous measurement of said individual's exposure to said stimulus; ∘ elapsed time since previous measurement of said individual's exposure to said stimulus; ∘ number of historic measurements of said individual's exposure to said stimulus that have been missed; • determining, by said central server unit, a next point in time for requesting said individual to do at least one of conducting a measurement of said individual's exposure to said stimulus and answering a questionnaire, based on said estimated risk, wherein the next point in time is determined so as to collect a time-line of stimuli exposure data that reveals onset patterns, frequency, duration and intensity of stimuli exposure; and • if said estimated risk is greater than a predefined level, transmitting, from said central server unit, a message to a third party, wherein said third party is at least one of: ∘ a health care provider; ∘ a family member or close relative; ∘ an employer; ∘ a law enforcement organization; and ∘ a governmental institution. ∘ a health care provider; ∘ a family member or close relative; ∘ an employer; ∘ a law enforcement organization; and ∘ a governmental institution.