Process to exit sandbox for M1 milestone

Hi Team,

We have successfully completed the work and test cases for M1. Do we need to work on M2 or M3 as well in order to exit the sandbox or can we get the production keys for just going live with M1?

Is a WASA needed for every milestone? So, if we go live with M1, will we need another WASA for M2 and M3?