Yes, you can convert from an Enterprise Account to an Individual Account. 

From within your Nestablish account

1. Click the gear icon next to your name and select Billing & Payments from the drop-down menu

2. Click the blue "Change" Button 

3. A box will pop up asking to you to confirm this change and to notify you that you must provide a credit card which will be immediately charged before continuing to use Nestablish.