Regardless the software, you should be keeping your workfile somewhere outside the software on your hard drive, in fact multiple hard drives if possible. There is ZERO benefit to keeping everything inside the software. Even for power users that use all the alamode bells and whistles, everything should be copied elsewhere.
In my case Total is where I create my report, however EVERYTHING related to the assignment is kept in a different folder on different drives (actually on a completely different operating system)...including the initial engagement, all correspondence, all docs, spreadsheets and calculations, the report in PDF, XML and finally a copy of the zap file.
You can open an alamode zap file without a subscription (at the moment). So worst case you've moved on to a different provider and let your subscription expire, now if you had to recreate the report initially created in Total in a different software, you still can from your workfile.
FTR, I've only been asked to modify a report over 2 months old ONCE in 21 years. When changing to a different provider, it would be smart to leave yourself 3-6 months overlap between the start of your new software and the expiration of the old.