In future is related to current affairs. For example, if you are late today and the teacher warns you to be on time for school in the future , use in future.
in the future is just an abstract concept, the phrases are in the near/distant future, soon/much later .
Oxford Example sentences
1. Please be punctual in future.
2. Who knows what will happen in the future?
In order to distinguish memory, in future can be translated into the future , from now on.
in the future translates to later .