To publish an app on Google Play, developers must pay a one-time registration fee of $25 USD for a Google Play Developer account. This fee allows developers to upload and publish apps on the platform. Beyond this initial cost, there may be additional expenses associated with app development, which can include hiring developers, using software tools, and building features. Marketing and promotional costs may also arise to boost app visibility and increase downloads. Additionally, developers should account for app maintenance costs, including regular updates, bug fixes, and performance improvements. Overall, while the initial fee is low, other costs may vary depending on the app’s complexity, target audience, and ongoing efforts to maintain and promote the app.