Definitions of put in:

• verb:   devote (time, effort, etc.) to a task

  Example: "He put in three hours every day at the hospital"

• verb:   make an application as for a job or funding

  Example: "We put in a grant to the NSF"

• verb:   break into a conversation
• verb:   set up for use

  Example: "We put in a new sink"

• verb:   keep or lay aside for future use
• verb:   to insert between other elements
• verb:   introduce