Thanks to sandboxing, the paid version would not be able to access data created by the free version, when trialing.
To avoid this problem in the past, authors offered the free version, and then paid unlock as a separate app package. So you could continue to use the original application you trialed, and the unlock package would turn it into the full version.
Unfortunately, this stopped when in-app purchases appeared.
To avoid this problem in the past, authors offered the free version, and then paid unlock as a separate app package. So you could continue to use the original application you trialed, and the unlock package would turn it into the full version.
Unfortunately, this stopped when in-app purchases appeared.