The short answer
Usually yes. LDL goes back up within a few weeks of stopping, and the benefit builds with every year it stays low.
That doesn't lock you into one medicine or one dose. Many people adjust over time, and if your diet, weight or other risks change a lot, your clinician may revisit the plan.
Please don't stop on your own. Talk it through first.
Source: Cholesterol Treatment Trialists' (CTT) Collaboration, Lancet 2010 and 2012.