Nitro Pro 12 Reverted to Trial Mode

[cb276 0]

I purchased Nitro Productivity Suite containing Nitro Pro 12 this past January.  Recently, when I opened Nitro Pro 12, it reverted back to trial mode.  When the "trial" ran out, it asked me for my serial number.  I typed in my serial number, and it said that the number could not be found.  I tried again to make sure I had not mistyped, and it gave me the same message.  Now, it says I have one day left on the trial, again, and I am dreading going through this a second time tomorrow.  How do I fix this? 

[AllainU 0]

Hello @cb276,

Thank you for reaching out to us through our Community Forums!

In order for me to further assist you with your concern, could you please provide the serial number of your Nitro Pro:

To send it via private message, hover your mouse on top of my name 'AllainU' and select 'Message'. 

Thank you very much in advance and I am looking forward to hearing back from you.