Netflix gained a record number of new subscribers in the fourth quarter.The ads plan, launched in 2022, reached 70 million worldwide users in November.Netflix is counting on ads to fuel its growth in 2025 and beyond.Netflix added a record number of new subscribers in the fourth quarter of 2024, as couch potatoes flocked to the streamer for popular programming like Christmas Day NFL games and season 2 of "Squid Game."But such massive growth in new subscribers can't continue forever (especially as Netflix pushed through another price increase this week). That's part of the reason many investors and analysts have been turning their focus to advertising, which they expect to fuel Netflix's next wave of growth.Netflix launched the ads plan which costs $8 a month after a $1 price increase this week in November 2022. The company said in November that the ad tier had reached 70 million global users. It said in its earnings release Tuesday that the ad plan makes up over 55% of new sign-ups in countries where it's available.When the ad plan first launched, the company cautioned investors that growth would be slow. Those days are over. Netflix told analysts it doubled its ad revenue in 2024 and expects to double it again in 2025, as it adopts tech that will make it easier for advertisers to buy ads."2025 is the year we transition from crawl to walk," co-CEO Greg Peters said on an analyst call.The ads era is still a relatively new one for Netflix. For most of its history, it eschewed advertising. That changed after it reported a subscription loss in 2022 that rattled investors. The ads plan has helped the company return to growth and cement its place as the king of the streamers, with more than 300 million global subscribers. It's also why Netflix has introduced more live programming like comedy and sports, which are popular with advertisers.The ads plan does more than add to Netflix's subscriber numbers. It can improve Netflix's average revenue per subscriber. The company has said it expected that figure to grow as it builds out its ads business.The ad plan can also sometimes keep subscribers from canceling by offering a lower-priced alternative. Netflix's standard plan is now $18 a month $10 more than its ad-supported one.Netflix's overall monthly churn rate, at 1.8% in December, was the lowest of the premium streamers, according to Antenna, a subscription data firm. Churn for the ads plan itself was higher, at 2.9% in December, though that is still well below the industry average.Netflix's ads tier can also serve as an on-ramp to a higher-priced subscription. A Wedbush Securities survey of about 1,000 people in December found that 10% of those with ad plans said they planned to trade up to an ad-free one.Of respondents who were not current Netflix users, slightly more indicated that they would definitely or likely consider subscribing to an ad plan (51%) compared with an ad-free one (38%). Wedbush Securities "Over the past year, our survey has consistently shown that new and returning users increasingly value the ad tier at least on par with the premium tiers," the firm wrote.