“Before you remove subscribers, try a re-engagement campaign to regain their interest. You might offer a special incentive to recapture their attention. If that doesn’t work, simply ask them if they wish to remain on your list and include an easy way for them to opt-out, or send a notification that their subscription period is ending and ask them to opt-in again. If the subscriber remains inactive, remove them from your list.”
Instead of writing off inactive subscribers automatically, try a re-engagement campaign first. Incentives are usually best, such as exclusive coupon codes and other deals and discounts. If such efforts fail, ask your subscribers if they would like to remain on your list or not.