1. At the proper time
   "she was duly apprised of the raise"
   - punctually 
2. In a due, fit, or becoming manner; as it ought to be; properly

See also: due

• keep one's nose to the grindstone
• keep one's shoulder to the wheel
• keep open
• keep out
• keep pace
• keep quiet
• keep step
• keep tabs on
• keep to oneself
• keep track
• keep up
• keep your shirt on
• keeper
• keeping
• keepnet
• keepsake
• keeshond
• keffiyeh
• kefir
• Keflex
• mince
• mince pie
• mincemeat
• mincer
• mincing