Frequently Asked Question:
Merge limitations
Is there a limit to the output PDF file size or number of files that can be merged using any of the Merge functions (MergeStreams, MergeFiles etc)?
There is no other limitation other than memory usage and disk space. All of the inbuilt lists are dynamic and expand as required. If you have a very large number of files to merge then you will most likely need to test it with your files to prove whether it works or not.
There is a 30 day trial which would allow you to test it if you don't currently have a license.