Free trial
After approval, Cloud and Solo include a 14-day trial. Cloud trial matches Medium (8 people, 50 GB), Solo trial matches XS (1 person, 5 GB).
After the trial your data remains. Under Settings → Subscription you choose a plan to keep writing. See After the trial.
The Offline product has no 14-day trial: after approval an unlimited license sits on the iPad. See Offline license and Solo, Offline, and Cloud.