This article describes that the trial and full subscription must match.
When a trial subscription is activated, it will not be possible to activate later a full subscription of another type. E.g. if you have a trial subscription for VM's 2 TB, you will not be able to activate a full 1 TB server subscription. You will receive a popup notification similar to the following
Cannot renew the subscription. There is no available subscription that can be assigned to the machine.
This message is absolutely normal and it means that there are no subscriptions of the necessary type.
You can either purchase the subscription that matches the type of the trial one that you have previously activated, or, as an alternative, contact Acronis Customer Central with a reference to this article. The respective team will wipe the account so that you could start over again with the right subscription type.
Please note in this case it will not be possible to preserve the data that is already on the storage.