I'm about to round a decade since MDMA came into my life. While I obviously didn't use every day I feel you on the sense that it's been part of my life for so long. I grew up through my experiences with it, and it will always be a part of my life. My life starts to feel weird if I go too long without a plunge. It gets more and more edgy, until I'm just like 'okay, it's time'.
Amphetamines have a spot in that they're milder, more real-world friendly, and can be used more often. They'll likely always have a place in my life, my summer of love in 2010 wouldn't have been much without it. Psychs were used too, but amp was something I could take, go out and have wicked days.
MDMA is more firmly rooted as something I'll use for the foreseeable future. I might feel that as I get older and 'grow up' some more, amphetamine will feel too immature to continue using.
I think all drugs that click with you will have a lasting presence in some way.