is the key important because i was given a key without a alarm only a common looking key

What is your question?

there is a red light alarm inside on dashboard when i was sold the 2000 mercury villager estate he told me i may have issues with removing the key just giggle it i went to hardware store and had 2 copys made with no issues but could it be that the anti theift device is looking for a click to open doors and my using a key to manually open the door is causing issues

What makes this problem better or worse?

driving made it worse overheating with 3 bottles of coolant

How long has your 2000 Mercury Villager had this problem?

It was sold as it is so from day one about two months ago purchased the van