Liberoffice buy for €9.88 is it one time payment or monthly? Thank you for help

I want to install in my MacBook and asking me buy for €9.88 is it one time payment or monthly? Thank you for help

Get a free download from directly from the project’s web site.

I’ve downloaded 7.6.6 362,2MB but also say buy

This should be a one time fee, covering at first cost of being available in the store (and Apple getting a share around 30%)
While I don’t know that AppStore I expect recurring fees to be clearly shown.

These versions are free software (as in open source) but there’s a small charge to cover the effort of putting software in the app stores, and to help develop the software (and build our communities).

Is cited from here:
https://www.libreoffice.org/download/libreoffice-from-microsoft-and-mac-app-stores/

Expect some changes, as Apple changes the models of payment currently (they are forced in European Union).
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Attention: If you wish to use Java-Extensions, HSQLDB in Base or the Reportbuilder in Base avoid the version from Appstore, as Apple does not allow this for the Version from their store.

Thank you I try