Making expiry dates optional can be performed on a per-customer and per-product basis.
At the time of writing, Expiry Dates will still appear throughout the application, however they no longer need to be entered if they're made optional.
Configuring the default for the Customer
By default, all Products are setup to have Expiry Dates turned on/off from the Customer Settings.
From the Edit Customer page, you can disable "Expiry Date required?" for all of the customers products in one go.
Note that each Product then has an option as to whether it defaults to the Customer settings, or overrides.
From the Edit Product page:
Changing a Single Product to not follow the default
From the Edit Product screen, you can configure how to handle Expiry Dates:
Updating Products in Bulk
Using the Product Export / Import, you can change the Expiry Date settings for Products in bulk.