Most OfficeSuite licenses are for a specific number of devices (e.g., 1 PC and 2 mobile devices). If you have already activated the license on the maximum number of devices, you will need to deactivate it on an old device before you can use it on a new one.
OfficeSuite uses license keys (single-user or multi-device) tied to account/device limits and activation servers. Activation failures typically result from network issues, key misuse, exceeded activations, mismatched account linkage, corrupted app state, or expired/invalid keys. mobisystems officesuite activation key fixed