There are many factors that can influence how long they last. For example:
How long are these electrodes used at a time (30 minutes or 8 hours). If they are used for a couple of hours a day, we recommend using 2 sets of electrodes. Use the first set the first day and the second set for the second day. This will give the first set about 24 hours to completely dry which will expand the usage time. Repeat these steps by rotating the 2 sets.
If you have a lot of body hair they will not last as long as if they are placed on bare skin. If possible place them on bare skin.
During a hot summer day you can sweat more than during a winter day. Once they get wet they will last less long. Let them dry for 24 hours which will extend their usage time.
As you can see there are many factors that can influence the usage time. However, following the instruction on the electrode bag will help extend the usage of these electrodes.