
Hi,
First of all, trials can't be extended undefinitelly. There is a limit and we are going to reduce it this year.
To your questions, the model created with a trial persist on the tenant and continue to be usable if the user extend his trial even after expiration.
We don't have a student program at the moment.
For these education use cases, you should contact a Sales representative to get a promocode instead which will add credits to your tenant for a defined period of time.