Yes.

When you create a new StableBit Cloud account, you will be granted a StableBit Cloud+ 30 day trial. While on this trial, any apps that you link to the cloud will also be automatically granted 30 day fully functional trials allowing you to explore and try out the apps in their entirety.

You can also start a 30 day trial at any time from within an app, after installing any app for the first time (whether it's linked to the StableBit Cloud or not).