Questions & Answers about Я хочу продлить подписку.
Russian has two aspects of verbs: perfective and imperfective.
- продлить – perfective (focus on the result, “to extend once, to complete the extension”)
- продлева́ть – imperfective (focus on the process or repeated action, “to be extending / to extend regularly”)
In Я хочу продлить подписку, you are talking about one specific, completed action: “I want to renew/extend the subscription (this time).”
So the perfective продлить is natural.
You might use the imperfective in a different context, for example:
- Я каждый год продлева́ю подписку. – I renew the subscription every year.
- Я буду продлева́ть подписку каждый месяц. – I will be extending the subscription every month.