Last forever? Nothing lasts forever. But it will certainly last as long as the threads aren't stripped, the plastic isn't cracked, (you can buy replacement plastic/glass/metal tanks though) and as long as everything else doesn't strip out or break. YES you can keep buying replacement heads as long as the device itself does not wear down, but of course it will over the months/years. You should always have a backup with vaping, or 4, or 5, 6, 7, 8, 9, 10, 20... lol, and this goes for batteries and vaporizers as well. You may want to buy another eGo battery once a month or every 2 months as well. (assuming you are using eGo batteries, that is) OR a new mod every few months.. New batteries.. etc etc... because we cannot go to the gas station to buy a new pack of vivi novas and you will not want the day to come where your only vivi breaks and you've got nothing to vape from. U can also learn to make your own coils instead of buying heads. But yes, it may break eventually. Its best to keep buying backups every month or so, even if your original is still going strong. You may even want to try more rebuildables with pre-made replaceable heads or try clearomizers like the CE- style ones, or even have a couple 5 packs of regular old cartomizers and some atomizers for JUST INCASE. You are not using disposible cigarettes anymore. Your using man made machines essentially, so you need to keep up with them wearing down.