How about asking first thing in the macro:
Option Explicit
Sub Testme()
dim pwd as password
'more declarations
'before you do anything
pwd = inputbox(Prompt:="What's the password, Kenny?")
if pwd = "topSeCreT" then
'keep going
else
'nope, get out
exit sub
end if
'more code here
End sub
You may want to protect the project to make it a little more difficult for most
people to see the password in your code.
Select your project in the VBE
Tools|VBAProject|Protection tab
Give it a memorable password
Note that there are inexpensive project password breakers available. You won't
stop all, but you'll stop most.