Steroids can remain detectable in a persons system anywhere from 1 week to over a year after use. For the most popular substances like nandrolone (deca, testosterona), one year is the usual time that they could actually be detected. For injectable testosterone, between 3-6 months is commonly sufficient. Luckily, for steroid users, the cost of a steroid test is very expensive and hardly ever done. If you are being tested for "drugs" 99% of the time a steroid test is not done. Random tests for college sports will test for them though (the cost is probably why they are random). People usually worry more than they should though. Even though a drug "can" be detectable, a lot of times they aren't.