Uploaded data (hard copies), ie; stories, photos, images, etc, *should* "sync" between the two applications (ACOM on-line member tree program and FTM/FTMM (latest versions)).
"Notes" are an entirely different story. There is no "Notes" field in the ACOM on-line member tree program, but there is in FTMM. Again, the two applications only share SOME data.
All uploaded data exists and is viewable in your tree(s) whether or not you have are subscribing to the ACOM collection databases.
Your tree on ACOM is not dependent on a paid subscription. When you cease to subscribed to the ACOM collections db's, any "links" you saved to your tree go dead, the citation still remains, but access to view the document/image associated to the link is unavailable. Those links will go "live" again, if you resubscribe in the future, however, nothing is forever.