Schedule of understanding
Short, because there is not much to say: you make animations, and there are limits on how many.
Any animation or still you make here is yours, to do with as you will: no rights are claimed over your pictures or over what is made from them.
Send only pictures you have the right to use, and nothing unlawful. An account that does otherwise can be closed.
Publishing a duet hands one of your pictures to strangers, so it carries rules that keeping work to yourself does not. Somebody else's private photograph is not yours to publish. Neither is anything unlawful. And a duet must not be a way to get at a person: no harassing somebody, and nothing about somebody who did not ask to be in it.
Any duet can be reported, by anyone who opens it, and any duet can be taken down. Taking one down does not touch the composition it was made from, which stays yours and stays here.
Every account has a daily allowance, and a set of designs and sizes it may render. The membership page says what each plan gets, and it reads from the same place the service does, so what it says is what is enforced.
Membership is monthly, bought and cancelled through Gumroad. Without a membership an account is on the free plan, and goes on working on the free designs.
This is a small service run by one person, offered as it stands, without warranty, and it can be interrupted or withdrawn. Nothing rendered here is kept for long, so download anything you want to keep.
Write to support@makesweet.com.