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It really depends on the use and if you wiped them down regularly to remove oils and sweat from them they could last for about a year with light use. I have 3 guitars so I do have one with a year old strings on it that I don’t play as much as the other 2. But many people will change them after a few months. Performers probably only do a single gig on a set of strings.
If they show visible signs of wear or have lost their ring and sound dull, change them! After you have some experience with your instrument you will just know it’s time because the guitar just doesn’t sound right.
There is a lot more that could be said about string changes, but there’s a starter. I just learned that a specific set of strings can make your instrument really come to life (as if those strings were manufactured specifically for your guitar).