Does the free trial have any limitations?

Yes. The Trial version is limited to 20 indexed tasks and 20 indexed documents. The limit is for a single repository. There is no limit on the number of repositories.

The limitation defines maximum number of indexed documents. When the limit is reached, the files are not deleted - it simply does not appear in the Keepmark, even though it is physically in this repository.

Adding files over the defined limit may cause that newly added/created files will not be visible in the repository.

Why are there such limitations?

It seemed to me to be the best and easiest way to limit the full functionality of the application for the purpose of presenting its features, without introducing additional mechanisms to the application that somehow reduce the privacy of users who have paid for the Keepmark's license (e.g. by verifying the license online at application startup).