For 30 days, Skype keeps all of your text-based chats stored in the cloud. If you’d like to keep a longer archive of your chat history, you’ll have to make manual backups. It’s not difficult, and it’s probably not necessary for most, but regular backups will ensure your chat history is always available on an external storage device, or in the cloud.
1. Open the Run command on your Windows desktop.
2. Enter %appdata%\skype in the Run dialog.
3. Click OK.
4. Open the file with your Skype ID. Depending on the version of Skype, it could have other words/characters but it’ll be the only one that contains your ID.
5. Copy the main.db file (might not have the .db suffix depending on your version) and move it to a safe location for storage.