5-7 days at the most. It is normally only detectable for a day or 2. Please read this www.erowid.org It does not stay in the system forever. Also, drug tests do not test for LSD.
How Long Acid Stay In Your System?
It stays in you forever my friends that did it quit years ago have people crack their backs and still see walls melting cause it stays in your spine and releases when it gets cracked