Once unlocked, there is an allowance for working offline as the same user for up to one month before the subscription must be reconfirmed. The runtime features will be locked if you are not signed into Unity, or you are a Unity Pro user without a valid subscription. When using this package, the Unity Editor will periodically check if you are entitled to use the runtime features. Unity Pro: Havok Physics for Unity subscription is required, available from the Unity Asset Store.Using the features at runtime may, however, require a development license depending on your Unity subscription plan: Havok Physics for Unity is free to download from the Unity Package Manager. The licensing and distribution model of Havok Physics for Unity is owned and managed entirely by Microsoft (Havok) and not by Unity.