This is the category marketers reach for when the asset does not exist yet and there is no budget for a shoot. It is also the category where the demo is furthest from the working day, because the showreel was produced from the vendor’s own prompts with unlimited attempts, and you will be working from a brief with a deadline.
The single number worth establishing in a trial is your acceptance rate. Every plan in this category is quoted in credits or seconds, and every one of those units is spent on attempts rather than on results. Four hundred credits at one usable output in four is a hundred assets, and that is the figure to compare against the tool next to it.
Model access is the second question. Many of these products are interfaces over models they do not own, which is a fair way to sell one subscription instead of five. It also means the output can change without warning when the underlying model is swapped, so ask which versions are exposed and whether older ones stay available long enough to finish a campaign.
Rights come last in the vendor’s copy and should come first in yours. Read what the licence permits for paid media and client work before the trial ends, because a free tier that grants personal use only is a licence you have already outgrown by the time the asset reaches an ad account.