How long does worcestershire sauce last?

Store bought, unopened and properly stored: a very long time (at least 18 months). Opened but well refrigerated: opinions vary, from 3 days to 3 months. The good news: in both cases, it doesn't...

About 1 month (As long as salsa does)

in the fridge? for practically forever.

Not long. If you keep it in an air-tight container and refrigerated you should still use it within a week after opening/making.

3 Years.