Since you are purchasing your own coverage, you must enroll in Medicare at age 65. Marketplace/ACA/Obamacare coverage is not considered creditable coverage. What that means, is that if you stay enrolled with your individual coverage and later go to enroll into Medicare, you will be penalized since you did not have "creditable" coverage. Therefore, you will receive a late enrollment penalty when/if you ultimately decide to enroll into Medicare Part B. Upon applying, your monthly premium may go up 10% for each 12-month period you could've had Part B, but didn't sign up.
(*The only time that it could make sense to continue ACA coverage is if you and your spouse do not qualify for premium free Part A based on work history)
See information here on Medicare.gov regarding this late enrollment penalty.
This piece from Medicare about Marketplace coverage is also extremely helpful.
Please realize that if you are receiving any Marketplace subsidies, those will cease upon your turning age 65.
You’ll need to enroll in A and B and determine whether or not you want a Medigap or Medicare Advantage plan.
You can contact our agency at 248-871-7756 and we can help enroll you into the Medicare plans that you'll need post age 65.
We have several ways to connect with us and learn more about Medicare. We have a private Facebook group where you are welcome to ask questions, our website has plenty of information and shows you other ways to contact us as well.
You can also email us at firstname.lastname@example.org.