Every account starts with credits, and the daily wheel adds a few more. That is enough to see what the model does with your own photograph before you decide whether this is worth money. It is not an endless free tool, and anything claiming to be one is either lying or about to close.
They are meant for one honest test. Spend them on the mode you actually came for rather than the cheapest one, because the point is to find out whether the quality is good enough for you, not to stretch the number of results.
The wheel can be spun once a day and adds a small amount. Over several days that accumulates, which is why some people use the site without ever paying. It is slow on purpose: the generation costs us graphics-card time whether or not the result was paid for.
One eight-second clip is a few minutes of a rented graphics card. A site offering endless free clips is either queueing you behind everybody else forever, or selling something other than the service — usually your uploads, your email, or an advertising network you did not ask to join.
The arrangement here is plainer: you buy credits in a pack, each result costs credits, and when they are gone the account stops until you buy more. Nothing renews by itself, so there is no subscription to forget about.
Use the largest copy of the photograph you have. Crop to one person. Pick a frame where nothing crosses the body and the light comes from the front. Those four things change the result more than any setting on the page.
If a result comes back wrong, read it before spending again: strange hands and smeared edges mean the model could not see enough, and the fix is a different photograph rather than a different mode.