Additional details. A light user with a single exposure would likely see it gone from their system within a week. However, the drug likes to seek out & deposit in fat stores in your body, so a heavy user could abstain for months & still have some leaking back into their blood & show up on a pee test.
The. The metabolites can be picked up on testing for weeks to moths later if you were a heavy user.
Body. Body fat has a lot to do with the components of marijuana staying in your system (the more you have it the longer it stays). As dr. Fowler mentioned it can take weeks even months; from my limited clinical experience about a a few weeks to a month on average (i often drug test clients who take prescribed controlled medications).