Most pickles are preserved with vinegar and salt, which helps them last. Once opened, keep them refrigerated and use clean utensils so you do not introduce bits of food into the jar.
A simple rule for many jars is to consume within several weeks after opening, and always follow the label guidance. Watch for changes in smell, texture or appearance. If something looks off, do not risk it.
Storage is not glamorous, but it matters. A good jar should taste as bright on week five as it did on day one.