Buying content without being locked in

Ask the questions before the invoice, because afterwards you have no leverage.

The standard was invented to protect buyers, and a buyer who does not check is not protected. A handful of questions asked before purchase determine whether the library you are building is portable or is quietly a rental with a longer term.

Ask which edition of the standard the packages conform to, and ask for one to test in your own system before committing. Ask whether the content phones home to the vendor's servers at runtime, because content that does will stop working when the arrangement ends regardless of what the licence says you own. Ask whether you receive the packages or a link to them.

Ask what happens at the end of the term. There is a considerable difference between a licence to use content while paying, which is a perfectly reasonable commercial arrangement, and an understanding that you keep what you have paid for. Both exist in this market and they are not always distinguished clearly in the conversation.

None of these questions is adversarial and a reputable supplier will answer all of them without difficulty. The ones that produce evasive answers have told you something useful at no cost.

One more question is worth asking of any supplier, and it is the least comfortable: what does an exit look like. Not whether the content is portable in principle, but the practical steps, who performs them, over what period, and at what cost. A supplier who has thought about this has usually built something portable. One who treats the question as premature is telling you how the end of the arrangement will go, at a point when you can still choose somebody else.