From what I gather the original trial model was 12 weeks and they followed up with people at the one year mark to confirm they still had the same results.
@Redknight mentioned he was going to see about prolonging treatment to the 18 week mark I believe to see if he garnered further results.
It may have been him also that mentioned in the future they may be looking to offer software upgrades for the device. Presumably, if they improved upon their timings or something and could offer further reduction.
So it appears they aren't looking at it as continuous use, but possible periodic need. Someone else had said something like what if you incur another noise trauma etc. In which case I could see another round of treatment.
As long as it turns out to be legitimate then I'd say it appears they have a goal of making it something with incentives to continue to bring in revenue, but not form dependency on it. Though they also have charges for tongue tip replacements after 180 hours use or something like that.
I'm sure to receive software upgrades would cost additional money plus the additional cost of clinic visits etc.
My word is by no means gospel. Just my interpretation of what's been presented.