Alimony in separation agreement surviving divorce

I have a legal separation agreement providing me alimony that ends with death/marriage/cohabitation.

My husband intends to file for divorce in July.

According to things I’ve read, I seem to have to do something to make sure there is a request for alimony before the court before he applies for absolute divorce.

How do I ensure that the alimony requirement is incorporated in the divorce agreement?

If you have a separation agreement that has been signed and notarized by each of you, you do not file a claim for alimony as it has already been established by contract, and the requirement that he continue to pay as per the agreement will not be affected by the divorce.
If you wish to have your agreement incorporated into the divorce judgment (making it a court order, and therefore modifiable) you must counterclaim in the divorce action to have the agreement incorporated. You should schedule a consultation with an attorney to see if it is in your best interests to have the agreement incorporated into the judgment, and to ensure the agreement itself does not bar you from doing so.