So, in order for you to buy life insurance on your spouse you would need your spouse’s consent/permission, signature on the application, and your spouse may need to answer some health question and take a physical exam, if required by the life insurance company.
Some life insurance carriers issue policies that can be applied for without the insured’s knowledge or consent.
You can be the beneficiary of your spouse's life insurance as long as there is an insurable interest. This means you have a financial interest in your spouse. Life insurance companies usually accept that a person has insurable interest in his/her spouse.
In addition, the issue would be how much in life insurance coverage you're applying for and if your spouse’s consent is needed.
There are some group life insurance situations or credit group life insurance situations where a small death benefit life insurance policy can be signed up for without your spouse’s knowledge - Usually something like a $1,000 to $15,000 in face amount of life insurance. A larger amount of life insurance purchased on an individual does require spousal consent to be insured.
Here's how to buy life insurance on your spouse.