Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Wouldn't turn things off until you have your MS 365 subscription. If you do, your OneDrive account will revert to a free 5GB account when it expires.
One other tidbit of honesty, am not really familiar with multiple subscriptions when it comes to recurring billing especially since right now you have a "trial" subscription. To me, it seems odd that <recurring billing> is an all or nothing kind of thing for actual purchased items.
You may want to pose that question to Microsoft Support. If it were me and I wasn't sure, would make sure I have a copy of everything on a local hard drive just to be on the safe side but I'm an overly cautious kinda guy when it comes to stuff related to my data.