For Subscription25 to work properly you need to add products to administrations. Which indicates that a product is available to use in that administration.
1. Replace Page Layout of Product
First off, we need to add some fields to the page layout for Product. Subscription25 comes with a default Product layout which has these fields included and which you can assign to profiles.
Navigate to the Object Manager in Setup
Navigate to the Product object
Click the Page Layouts tab
Click the Page Layout Assignment button
Reassign the Subscription25 page layout to the correct profiles
There should now be a button on a product called “Manage administrations”
2. Manage Administrations
When you navigate to the “manage administrations” page by clicking this button you should see something like this:
This allows you to specify this product is available in an administration and which VAT Rates apply, which ledger is related to the product and what kind of performance type this product is.
Add the product to every administration which is allowed to sell this product