One single key can have multiple transactions - e.g. each time the key was used for a new installation or a regular online check was done, a new transaction for this key is generated. The transaction list gives you a complete history of the key usage.
In the example below the transactions tell the following story:
•Alisa made a product activation on computer mirageoffice2-pc3.fritz.box and it was successful
•There was a manual product activation by e-mail
•The computer mirageoffice2-pc3.fritz.box was deactivated
•The column Next date of license check indicates, when the next online check would be due. This is only relevant if the online check is enabled in the application