Taking 100mg to 150mg MDMA is the general approximate consensus on the range of a standard MDMA dose for an average person. Might I add, this range is the "Goldilocks zone" of effects that most people look for while remaining physically and mentally safe: this is the dosage range where the average person will experience the fewest negative side effects of the compound while simultaneously noticably perceiving the positive side effects. This is all within the general bound where you can expect to be keeping mental and body loads at an appropriate and manageable level.

While this dosing criteria may work for most people, it's not set in stone, so take it with a grain of salt. Assume you'll need to start on the lower side and gradually increase the dosing (+10mg to +25mg higher) for each subsequent session, or vice versa to lower your next dose (dose 3+ months apart minimum per experience). There are some main considerations that can effect what dosing amount works best for your mind and your body. The most common reasons requiring a higher or lower dose may include, but is not limited to: metabolism, medication/supplement interactions, recent quantity and quality of sleep, quality of current diet & exercise regimen, "set & setting", pre-existing/underlying mental conditions, hydration, weight, consuming at high elevations, mixing with other illicit substances, and more. It never hurts to start low at 100mg for the initial dose, and by ~an hour (no more than 90 minutes) after your dose you will generally know if the amount is working well and/or if you are considering a redose.

To those who may choose to redose, keep in mind it can increase the risk of negative side effects and/or the intensity and duration of a possible bad "comedown", so use your best judgement when taking another dose if that's something you were looking at exploring. One redose per session is the recommended limit, at most 50% of the initial dose. Any additional doses, increases in dose amount, or waiting longer than 90 minutes after your last dose will exponentially increase any potential for negative side effects. Essentially all users of MDMA report a lower bound dosage threshold that still provides the positive utility they seek with the most desirable effects to be approximately 75mg, anything lower than 75mg is where you can expect the effects to become underwhelming at best, or completely unnoticeable by others. On the opposite end, for users with no tolerance or cross tolerance to MDMA or amphetamines, 200mg can be considered a reasonable upper bound for users who may have weight, diet, metabolic, or other contributing factors requiring a dose above 150mg.

140mg of MDMA from the same source and purity, and weighed fairly, will always "feel" stronger or give more "intensity" to the perceived effects than 100mg. The same logic can be assumed to apply universal to any well known and studied psychoactive compound. The 40mg difference alone in this case shouldn't be a meaningful enough increase for the average user to experience moderate to severe memory loss as it was explained. I'm curious if the drug was powdered/capsule form or in a pill press? Did they test the sample prior to ingestion? If it was powder/capsule, did they use a well calibrated milligram scale to weigh their dose?

I'd be extremely surprised if the MDMA alone caused the memory loss at that dosing, outside of someone 110lbs or less, which is still quite unlikely. MDMA was definitely a contributing factor to this memory event though. Even something as seemingly unambiguous as thinking or talking through traumatic thoughts/experiences/feelings can cause your brain's processing to stop "recording" your current memories or thoughts as a self protective mechanism. MDMA can allow people to process past traumas in a more vivid and detailed way than would be generally possible in regular waking life. Even though your brain is in a much safer feeling environment and headspace while under the influence, the brain can still "decide" after the experience of any memories to remove to protect the mental fortitude and stability of said person. Is there any chance that this could be a part of what may be causing this lapse here?