If you smoke it occasionally it will remain in your system for up to 10 days. If you smoke marijuana on a regular basis it will stay in your system for as long as 45 days, and if you smoke marijuana at a constant pace, it can stay in the body for 90 days, Marijuana is fat soluble.annabinoid metabolites appear in urine within two to fo â¦ ur hours after smoking marijuana and may persist up to 30 days (at the 50 ng/mL cut-off concentration) depending upon a person's previous pattern of abuse. In general, infrequent use of marijuana may only be detected for 1-3 days after use.