Here's an Autodesk document on how to make and edit an options file. Included in this is how to control the maximum borrow time. I would recommend setting this to a day or less because of issues when returning borrowed licenses.
the following is from this Autodesk tech doc...
Creating the options file
Create a new text file named ADSKFLEX.OPT. It is strongly recommended that you only use a plain text editor, such as Notepad, for editing options files.
Place this file in the same directory as your Autodesk license file.
Perform a ReRead License File operation from the Start/Stop/ReRead tab in LMTOOLS.
Examine the debug log file to confirm that your options file changes have been implemented by the license manager.
Setting the borrow period
You can specify the maximum duration of time that a specific license can be borrowed for in hours. This value cannot be above the maximum borrow period specified by Autodesk in the product license file.
MAX_BORROW_HOURS [productfeature] [hours]
The following example limits license borrowing of AutoCAD 2006 licenses to 3 days:
MAX_BORROW_HOURS 48800ACD_2006_0F 72
Book of the day...