Preheat oven to 325°F (165°C). Mix almond flour, melted butter, and sugar substitute, and press into the bottom of a springform pan. Bake 10 minutes, then cool slightly.
Beat cream cheese and sugar substitute together until completely smooth.
Add eggs one at a time, beating gently after each addition, just until combined.
Mix in sour cream, vanilla, and lemon juice.
Pour the filling over the crust.
Bake 50–55 minutes, until the edges are set but the center still jiggles slightly.
Turn off the oven and let the cheesecake sit inside with the door cracked for 1 hour.
Chill at least 4 hours, ideally overnight, before slicing.