You bought permission, not a file
Downloading a template or a photograph transfers no ownership. The creator keeps the copyright; you receive a defined permission to use the work in defined ways. Everything that later goes wrong with bought assets traces back to treating the file as the purchase and the licence as paperwork.
Four questions decide almost every case. Scope: one end product, or many? Scale: is there a cap on print runs, impressions or users? Duration: perpetual, or only while a subscription runs? Transfer: can the licence follow the site when you hand it to a client? Marketplaces answer these very differently — a royalty-free purchase is usually perpetual and per-product, while a subscription typically licenses each use only while you keep paying.
Register as you go, not at renewal
Subscription libraries generally require each use to be registered to a specific project while the subscription is active. Do it at the moment of use. Trying to reconstruct which of 200 downloads went into which client site, in the week you plan to cancel, is a genuinely miserable afternoon — and an unregistered asset in a live product is an unlicensed one.
