Can I lose my legal non-conforming use status if I stop using my property that way for a while?

Yes, this is one of the more common ways legal non-conforming use status is lost. The protection generally exists only so long as the non-conforming use actually continues; if it's discontinued for a meaningful period, municipalities generally treat that as an abandonment of the use, after which the property becomes subject to the current zoning bylaw like any other property, and the previously protected use can no longer simply resume without a new approval, such as a rezoning or a variance.

What counts as a meaningful interruption is fact-specific and can depend on the municipality's own bylaw provisions and the circumstances of the gap, including whether the interruption was genuinely a stoppage of the use or more of a temporary pause for something like renovation or a change of tenant within an otherwise continuous operation. Because the consequences of losing this status can be significant, particularly for a use that would no longer be permitted under current zoning, an owner who anticipates any gap in an existing non-conforming use, whether from a vacancy, a sale, or a temporary closure, should get legal advice about how to document continuity or minimize the risk before the gap occurs, rather than after the status is challenged.