You can manage your mobile devices within your Account Settings for your LastPass account.
Each time you successfully log in to LastPass using a mobile device, a randomly generated unique identifier for the mobile device (UUID) will be added to a list on the Mobile Devices tab. All devices listed here can be renamed, enabled, disabled, or deleted. If you rename the mobile device's UUID, be sure to click the Save icon to save your changes.
To restrict which devices can log into your LastPass account, click Enable, to restrict access to all mobile devices except those allowed to access your LastPass Vault, click Disable at the bottom of the window.
LastPass does not restrict mobile login by default. Learn more about managing mobile devices.