There are more than one subscription plan.
Each has a different price.
The more expensive it is, the more features you get.

The most popular plans at this moment are Microsoft Office 365 Personal and Microsoft Office 365 Family.
Each comes with a free 1 TB cloud storage.
Saving documents to the cloud storage can also be done without having to open a net web surfer.

Popular alternatives like LibreOffice exist and it is available for free.
The collaboration features are top-notch and the cloud storage is secure with a personal vault and a ransomware detection.