This is an OS side that affects Kindle devices. The solution seems to be:
1) Restart the device
2) Make sure that Wi-Fi is enabled/connected
3) Perform a Kindle sync operation (apparently this is either a menu item or icon on Kindle devices)

More at:
https://www.amazon.com/gp/help/customer ... 65NS4SUCJX

The version I have is 1.1.3.0554 and I've downloaded it from Amazon.

And I have only the MM icon available.

Hi,
this message is system message. It little weird that it needs to verify your license. Did you download Pro version from Amazon App store or from Google Play Store?
What version of MMA do you have?
MediaMonkey Pro app is only license for MediaMonkey and its launch icon should disappeared after first launch.
Do you have available both launch icons (I mean MediaMonkey and MediaMonkey Pro )? Try to use MediaMonkey launch icon instead.

Martin

Hello,

Sometimes, when I try to use MM Pro (without internet connection), a message opens saying "The license for this app needs to be refreshed. Please try again", and then de app closes.

I understand that, because I'm offline, the MM pro app could not update license info, but why close the app? Why not just keep MM on a "free mode" until I connect my cellphone again? It happens often when I'm driving, so I can't just connect to the internet just so MM can validate the key.