Thanks for your request. There is no limit of number of pages or document size. But you should note, usually Aspose.Words needs few times more memory than document size to build model of the document in memory. Memory usage depends on document size, format and document’s content.
So in your case the only way you can process really big documents if you give more heap space to your Java virtual machine. Aspose.Words will take loads of memory when loading/process the document, but when you finished processing the document, all memory will be released and garbage collected quickly. So it will be only a short spike of high memory use.
Also, I would like to say that producing huge MS Word documents is not very good practice. Ms Word does not like huge documents. Usually it takes a lot of time to open such documents in MS Word and sometimes MS Word just hangs. Normal size of MS Word documents is 100 – 200 pages.