Yes. When you protect a document or product you can specify the date at which it expires. When a customer registers they can then view your protected files until that date is reached. Once this date is reached the content will expire (if the content expires, it can no longer be viewed) and they will need to come back to you for a license to continue viewing the document or product.
You can also set customer accounts to expire on a certain date. The difference here is that any protected files published during their subscription period that you have authorized them to view can still be viewed after their subscription period has expired – they just won’t be able to view any files published before or after their subscription period unless they come back to you for a license.
So to summarize, you can either expire protected documents or products (and they are no longer viewable once they expire) or you can expire customers (and they can continue to view the documents/products that they were authorized to view during their subscription period).
Of course, if you have forced your customers to connect to the administration server before they can view your protected files then you can instantly suspend their account and this instantly revokes access to your protected content.
You can assign documents or products to publications for simpler management so specific customers can view everything assigned to a particular publication or you can publish documents / products on their own. If your customers have not been licensed with the correct keys then they cannot view your protected files.