if we develop a Desktop AIR Application,
do we have to pay any "license fees" to Adobe
in order to be "allowed" to use it ?
No, license is not requred as such. You can distribute it..
When you create and installer for your AIR app, you will be asked for certificate (which you can create on your own).
Further if you want you code/app to be signed (Authorized) you can get a digital certificate from any certificate provider as Thwate etc..
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