Roxo, she did say she forgot to edge herself and came "a bit", seems like the hypnosis is dependant on the person consciousness, so it can mismanage, the order was to not cum but she still did.
MC said he could only use the sticker on one person but this chapter makes clear he can give a girl a order, detach it and use it on someone else, I think that the previous victim will continue to follow the order routine until is done, as she was already used by MC he probabyl simply told her to do the usual until the sticker is placed on her again.
So he could have a loyal harem of sex slaves but decided to stick to one at the time, the order is permanent so memroies will not return, in the ending chapter is shown that even after being freed MC didn't remove the edging order, likely forgotten it, so she continues to masturbate but not finish, a lifelong torture.