Ever since Microsoft first outlined its plans to make its new Office available for purchase on a subscription basis (back in July 2012), more than a few users have asked what will happen if and when users discontinue their subscriptions.
In the case of Office 365 Home Premium and Small Business Premium, if you stop paying for those SKUs after a year, you'll have a grace period to figure out what to do with your stored information. In the case of Home Premium, users will be able to download their saved SkyDrive- and/or locally-saved data, open it with Office Web Apps and read/print it for some set period of time. (Microsoft isn't currently specifying how long that will be.) In the case of Small Business Premium, you'll have some kind of currently-unspecified grace period, as well, when you can access, read and print data stored in SharePoint Online.
For users with an Office 365 Home Premium subscription, as the expiration date of that subscription approaches, users will receive notifications inside the Office applications and via e-mail to remind/nag users about the approaching expiration date.
Once the subscription expires, the Office apps will enter a "read-only reduced functionality mode." This means users will be able to view or print documents, but won't be able to create any new documents or edit existing documents.
Users who want to regain their full Office capabilities will be able to purchase a new subscription (via Office.com) or a set of predesignated retailers. Users also will have the choice of simply using older, existing versions of Office or to just use the free Office Web Apps on SkyDrive for basic editing.
If a user has stored documents created/edited with Office 365 Home Premium in their SkyDrives, these documents will still be downloadable once subscriptions expire. Users can save SkyDrive documents to another computer or drive at any time, according to Microsoft. (With Office 365 Home Premium, users get an additional 20 GB of storage on top of their existing SkyDrive quotas.)