The free Speech service instance allows a limited amount of audio hours Speech-to-text each month. The specific limits, such as the number of audio hours allowed per month for free, can vary based on the details of Microsoft's pricing and the service terms.
I recommend checking the official Azure Speech service documentation or contacting Microsoft's Azure support. They can provide you with the specific terms and limitations associated with your free tier subscription and whether it will continue to be free for the next year. Keep in mind that these terms may change, so it's essential to refer to the latest documentation or communication from Microsoft.