Hi,
Do you mind sharing us the whole error message?
According to your description, I suppose that you might use the same email account which you used to purchase Office suits to get the trial version.
Try to log into Office.com website and check which account is displayed on the right hand top of the screen.
If it displays a different account you may sign out and sign in with the account which is used to purchase Office suits.
You may also follow the steps below to activate Office 2013 and check if it activates and works fine:
Activate office 2013 using the product key option by follow the steps below:
Open Word.
Click on File, Account,
on the right hand side on the page under Product Information check if the product is activated.
If not, click on Activate Product and select the option product key for Office 2013 to activate the program.
Hope it's helpful.
Regards,
George Zhao
TechNet Community Support