get Auth token with AppKey and Appsecret error

Hi there. I didn't find a way to generate a token, I accidentally deleted the old eternal token, now it can't be restored. And new tokens live for 4 hours. All software and applications have stopped working, customers are complaining. It is clear that I'have to find another service for applications. But I haven't found yet, do you know a third-party service that would pull tokens from the dropbox by Appkey and AppSecret. My applications are installed on devices that do not have access to the browser, it is required that the application does not require authorization data. Everything should be sewn in. And this is impossible with the current policy of Dropbox.