Stop License Acceptance popup by Auto Accepting Nuget within visual
studio
As I know, for now this is not a supported behavior in VS IDE. VS IDE itself doesn't have this option to turn on/off auto-accepting the lisense of one nuget package.
If I have to install 5 nuget packages, it shows up 5 items.
Whether a License Acceptance popup
will show up in Visual Studio actually depends on whether the author(s) of the nuget package asks it to do so. So this behavior for now is only controlled by the authors of the nuget package, not VS IDE.
Let me describe it for you:
When one developer wants to generate one nuget package from his project, he can uses xx.nuspec to define the metadata of the package to be published. He can set the package ID,Authors,version,description...
in it. After he use something like nuget pack xx.nuspec
or other similar pack commands, now the package he developed containes the metadata.
(A xx.nupkg is a xx.zip file, rename it to xx.zip and open it we can see its content)
After that he can publish the package to nuget.org
or other feeds, then when we consume it in VS we can see the metadata like:

#1.Now let's talking about the Main Cause of the behavior you met. See requireLicenseAcceptance:
This is one element the author can specify in xx.nuspec
file to determine:
A Boolean value specifying whether the client must prompt the consumer to accept the package license before installing the package.
So the behavior you met is controlled by authors, not IDE.
#2.To respect the choice of the authors who developed the packages, VS IDE will prompt the License Acceptance popup
when we install one package whose author sets the requireLicenseAcceptance=true
.
#3.As for the auto accept license
that you mentioned in the question, we don't recommend that you auto-accept all of them. As Matt described here: Not all NuGet packages are free on nuget.org
but(though?) a lot of them are free. So some packages may have special lisense that need us to review.
And actually as I know, there's no option from VS IDE or VS extensions is supported to do that...
In addition: There's an open discussion about the requireLicenseAcceptance
property in Github/nuget
here. You can track that issue and get the notifications if there's any update.
Hope all above helps and feel free to correct me if I misunderstand anything:)