Preheat oven to 350°. Grease 9-inch Springform pan. Line bottom with parchment paper (optional). Wrap bottom and sides of pan with foil if worried about leakage (optional).
Stir almond flour, melted butter, erythritol and vanilla in a small bowl until well combined. The mixture will be crumbly.
Press the crust mixture into the pan bottom. Bake on center rack of oven for 10 - 12 minutes until just golden. Allow to cool 10 minutes.
Meanwhile, using a stand or hand mixer, beat cream cheese and powdered erythritol at low speed until fluffy. Beat in eggs one at a time. Add lemon juice, zest and vanilla. Beat until well combined.
Pour filling into prepared pan. Bake on center rack of oven for 45 - 55 minutes until center is almost set. (will still be slightly jiggly in the center).
Remove from oven and allow to cool in the pan. Keep in the pan, cover and refrigerate for at least 4 hours or overnight to fully set.
To remove, run a knife gently around the sides, unclamp and carefully remove the pan. It should come right off.