You’ll have to choose whether you want to use LastPass on computers or mobile devices You won’t be able to use it on both unless you pay for the premium version.
If you use it on both computers and mobile devices at the moment, choose which one to keep. The first time you sign in to LastPass on or after the 16th, it’ll record which device you do it on. That will become your free device type – so if you sign in first on your computer, you won’t be able to use the app any more (and vice versa).
To keep access to both, you need to sign up for the premium version. If you upgrade before the 16th March, a full year costs £22 or £30 after.