To avoid issues with incompatible dependencies, we recommend using vgo.
Assuming you're working on a project github.com/your-username/your-project:
go get -u golang.org/x/vgo
cd $GOPATH/src/github.com/your-username/your-project
vgo mod -init -module github.com/your-username/your-project
vgo get github.com/TheThingsNetwork/go-app-sdk
vgo mod -vendor
See the examples on GoDoc.
Source code for The Things Network is released under the MIT License, which can be found in the LICENSE file. A list of authors can be found in the AUTHORS file.