Properly seasoning a cast iron or carbon steel wok will make it completely non-stick and protect it. A well-maintained wok should last you 10+ years.

Season your wok as soon as you buy it, and repeat the process only when you feel the wok has stopped being non-stick.

With proper use and maintenance (brush it out as soon as you're finished cooking, don't wash the wok with soap, and make sure it's dry when you store it) you should only need to season your wok once when you buy it, and perhaps again every couple of years after that just if something goes wrong.