I haven't used a whole sachet as yet, in comes in an applicator tube which you insert in you 15mins before

and squeeze out, so I don't think it would be too hygenic to leave it and then re-insert again as may cause infection (maybe just me being overly cautious). Always have enough left over for hubbie to use - there is quite a bit in each tube. Other preseed users may tell you different, just my experience - good luck! x.