No! If you’ve already bought a Eurail Pass, you don’t need to do anything. Mobile and Paper Passes that are already issued as Eurail Passes will continue to show the product name Eurail and will continue being accepted as a valid travel document.
If you haven't activated your Pass yet, you can start your trip within 11 months of your purchase date (or within 3 months for Plus Passes). Once you activate it (or if your Pass is already activated), it will remain valid until it expires. In short: you can use your Pass exactly as planned.