If my game is free but contains (non-required) paid items, should I pay the 5% profit as well?
Yes, you will owe royalties on all gross revenue, including those items listed in Section 5.b of the EULA:
b. Gross revenue resulting from any and all in-app purchases, downloadable content, microtransactions, subscriptions, sale, transfer, or exchange of content created by end users for use with a Product, or redemption of virtual currency, either within a Product or made externally but which directly affect the operation of the Product;
answered Dec 21 '18 at 01:55 PM
Follow this question
Once you sign in you will be able to subscribe for any updates here