Can drug abuse in the past cause hallucinations in the future for a teen, even when the drug abuse has stopped?

Yes. Yes. But this has nothing to do with being a teen. Some drugs simply hang around much longer in the brain (and other tissues) than one would reasonably desire...Whether one is a teen...A middle-aged guy...Or a bona fide member of the aarp...Or not...
No. Hallucination could be some other psychiatric illness which might be an underlying issue need psychiatric evaluation to understand the reason.