Google Play and Apple Store stores work with "tier" pricing, meaning that those who offer products within an app do not choose the exact value for which those products will be sold. It is necessary to fit the package created within one of the pre-defined store prices.
For example: if the first "level" of the store is $ 4.99 and the second is $ 7.99, but you want to offer a package at $ 5.99, the product will be placed on the second "level" and sold at $ 7.99. The "level" of sales will never be lower than the value given to the product, so it would not decrease to the value of $ 4.99.
iOS and Android have different "levels," so PK XD packages may have slightly different values depending on the platform on which you purchase. Either way, you can use your account and purchased items wherever you prefer.