I think so, because it's a vocational licence rather than a DoT(?) one. Where there may be a problem is if employees are expected to drive FLTs on public roads.
If you drive only on private property you do not need a driving licence to drive anything, if a 3 year old could reach the pedals they could drive on private property.
Previous posters are right BUT there may be a condition on your employers insurance that specifies only people with current licences can drive. It's unlikely, but a possibility, so do tell your boss that you've lost your licence. If you don't and have an accident, you and he could be in bigger trouble.