... until you stop taking the drug.
Now, MDMA isn't particularly prone to causing addiction. It is prone to causing lasting changes in how people relate to themselves and others, and a combination of personal anecdotes and studies suggest it's for the better.
> A long-term follow-up of patients who received MDMA-assisted psychotherapy revealed that overall benefits were maintained an average of 3.8 years later.
(This is after 2 total sessions)
See here for more http://www.mdmaptsd.org/infographic.html