The destination must be current
A button should go to the exact checkout or marketplace listing that the owner intends to use. Old test links, draft listings and unverified payment pages should stay out of the public build.
The offer must be understandable
The page should make the format, compatibility requirements and digital-delivery method clear before a visitor pays. If the product is a spreadsheet or local calculator, say so plainly.
The handoff must be supported
A sale is not complete when a payment succeeds. Support routing, delivery instructions and refund or remedy information need to match the chosen platform and the approved legal position.