In your CleverReach account you have the option to separate single projects/websites by using separate recipient groups/forms.
You can create up to 100 recipient groups to efficiently manage your data. By doing this you can spread your recipients over multiple lists and use database fields independently per group. Within any group you can alter the general settings, segment a subset of recipients, configure unsubscribe information and much more. Here is an example for a separation of projects by language.
For the single groups you can then create separate signup and unsubscribe forms.