Have you activated on more than two machines or more than two times?
Please refer to :
If you have any trouble to launch your Adobe product and has been revert to trial and/or prompt for a serial number, please try the steps below:
1. Sign Out and Sign In back following the steps:
2. Delete the OPM.db file:
3. Reset your Hosts File: (follow the steps 3 from the link below)
Please, let me know how it goes and if the issue still stand after following scrupulously the given steps.