@Eduardo Fávaro You can create a free Azure Speech service with the initial 200$ credit which is provided for 30 days. The keys from this resource are used to call the TTS or STT API's with the required data, based on the number of calls made to the service you will be charged accordingly and if the number of calls or billing is higher than 200$ then you need to upgrade to a pay as you go option and continue to use the service.
With respect to other services like ANKI or AwesoneTTS, these are not supported under Azure but you can try to integrate your Azure speech service with calls to the REST API.