The news seems to be correct as both the posts support their claim with an email (which has the same content) from the Nokia Messaging team. The content reads
Thank you for participating in the Nokia Messaging beta trial. We have enjoyed serving you, and have learned much from the feedback and input from you and tens of thousands of Nokia phone owners. This message is to inform you that the trial period will come to end at the end of
September and may not be available on your operator network.
Please keep in touch with your operator about this service availability. Thank you for using Nokia Messaging and we look forward to serving you again in the future.
Nokia messaging team
Personally I have not received any mail regarding the end of the free trial for Nokia Messaging. If the trial ends I would not subscribe to the paid service as there are better options available, for example the Gmail app and the Emoze
What would you do in case Nokia decides to end the free trial for Nokia Messaging?