I need a quick answer to the license question

To quote Royalty Free license agreement : Royalty Free License allows you to use the product without the need to pay royalties or other license fees for multiple uses, per volume sold, or some time period of use or sales.

Simply, the answer is yes. But this applies only to product with Royalty Free License, some products have Editorial License and you need to watch out for that. There is also a Custom License, if your English is not that good you should buy only Royalty Free License products.

Don't forget royalty free license provides “limited” commercial uses.
There are restrictions on some commercial uses, for example, its not allowed to sub-license/redistribute the work, e.g. selling it as in game items, or embedded in some other stock media products (e.g. modkits, kitbash sets, modular sets for games, etc).

If the boundary's for a give commercial activety are unclear then its best to ask for clarification from the creator/owner.

can

yes