Hello Mrudula Menon,
Thanks for reaching out. Just to make sure I point you in the right direction — could you clarify where exactly the "renew subscription" message is appearing? For example, is it inside the Minecraft Launcher, on the Microsoft Store page, or somewhere on minecraft.net?
The thing is that Minecraft Java Edition itself is a one-time purchase with no recurring fee, so the prompt is likely either related to Minecraft Realms (an optional multiplayer add-on that does have a subscription), or a case where the launcher isn't recognizing your license — possibly because it's signed into a different Microsoft account than the one you used to purchase. Knowing where the message appears will help narrow this down quickly.