This depends on a few things really. Firstly, how long your e-liquid lasts will largely depend on the amount you vape. Obviously, the more you vape the faster your e-liquid will run out!
The type of device you use will also heavily influence the amount of e liquid you go through. For instance, pen-style starter kit devices will use up a lot less e-liquid than advanced sub-ohm kits.
If you’re just starting out then you can expect a bottle of 10ml standard nicotine e liquid to last you a few days. On the other hand, if you’re a heavy user with a sub-ohm kit then you might go through that in as little as a day.
If by ‘how long does e liquid last?’ you mean the amount of time it’ll take to deteriorate, most good-quality vape juices should last 1-2 years.