I doubt it will make you dependent. It's more likely that the efficacy of ZMA in terms of sleep will decrease over time. In other words it will provide less help with sleep. You see that with other natural sleep aids like trytophan and melatonin, too.

If you have trouble sleeping and the ZMA helps, then I'd say stick with it and then if it stops helping rotate other things like trytophan, but while still taking the ZMA for it's other effects.

Incidentally, anytime you are taking a sigificant amount of extra zinc (more than 40 mg long term) it is possible it will precipitate a copper deficiency. They compete with each other both intestinally and biochemically. Copper is important for growth so it's something to think about.

The RDA ratio is supposed to be 1 to 1. That means around 2 mg copper to 15 mg zinc.

I'm not saying you should be worrying about exact ratios and interactions in everything you take. That would be ridiculous. But this is a an important one.