No one in this user-to-user forum can help you with an activation issue.
You need to contact Adobe Customer Service by phone and inquire what the nature of the error is. Perhaps they detected other copies running on the same serial number, or maybe a routine check detected an invalid serial number.
At any rate, only Adobe can help you and this forum is not the way to reach them.
I completely agree with Station_Two.
I know of no Adobe programs, that are time-limited, beyond a trial version.
However, there can be many reasons, why Activation might fail. Adobe C/S can usually fix those, in but moments.
As an example, an assistant used PS CS2 on his laptop. When he would connect to my IP server, he was assigned a random IP address, which did not match that in his Activation data. After two failures, and re-Activation by C/S, they made some changes in his Activation data, so that from my network, he would not loose it. That worked for several years, with no other issues. All sorts of issues can cause Activation problems.