Keep the number of the application form, in order to follow up the process.
“以便” yǐ biàn is a formal way to say “in order to ”. It is normally used to express a purpose or an outcome of a particular action. Here are two examples:
|(You) need your passport and some cash||in order to||deposit in your account.|
|Keep the number of the application form,||in order to||follow up the process.|