There was a connection issues.

[Kelsey Rush]

I'm having trouble activating. I know this has happened before and I ended up just buying a new license because I couldn't figure out how to activate.

[Reymund Oyong]

Hi @Kelsey Rush

Thank you for reaching out to us through our Community Forums!
My apologies for any inconvenience this issue has caused.

Please perform the following steps so you could activate your Nitro Pro 13 using version 13 serial number.

1. Download Nitro cleanup tool from the link below:
https://install.nitropdf.com/professional_13400811/install-cleanup/install-cleanup.zip 

Please note that this cleanup tool will remove all traces of Nitro Pro including your customize stamps. If you have customized stamps, please refer to the link below about how to transfer/backup stamps:
https://kb.gonitro.com/knowledgebase/#/search/stamp/000004307 

If you do not have customized stamps and quicksign signatures, please disregard the above link. 

2. Extract the cleanup utility then run the cleanup tool by double-clicking nitro-cleanup.vbs. A command window will appear during the cleanup process.
3. After the cleanup, restart the computer. 
4. Install Nitro Pro 13.40 by downloading a new installer from the link below (delete the previous installer you saved on your Downloads folder):

https://www.gonitro.com/nps/product-details/downloads - Click the 'Download Nitro Pro 13' link. 

5. Once Nitro Pro 13.40 is installed, activate it by going to Help tab > About Nitro Pro > Activate. Enter your version 13 serial number then click on Activate. 

Kind regards,