Since there is a lot of citrus juice in lemon curd that is high in acid, it is perfect for canning in a water bath. The National Center for Food Preservation specifically says that lemon curd is safe for canning. However, their recipe is slightly different than mine in that it is a larger yield that makes sense for canning. It also calls for bottled lemon juice which has a standardized acidity (fresh lemon juice is not recommended) and superfine sugar instead of granulated sugar. Bottom line, if you want to preserve your lemon curd, use a recipe that is specifically for canning.