Every step below is from an official source
Switch from 1Password to LastPass
What to do at 1Password before you leave, what LastPass needs when you join, and everything else the switch touches. Your full plan is built in your browser and stays there.
Official sources reviewed . How we review sources
At 1Password, before you leave
Export from the 1Password desktop appBefore
On a Mac, open and unlock 1Password, select File > Export and choose the account. Pick 1PUX or CSV, then select Export Data.
How to export your data from the 1Password apps1Password Support. ReviewedExport passkeys from the iOS or Android appBefore
1Password says passkeys can only be exported in 1Password for iOS and Android at this time.
How to export your data from the 1Password apps1Password Support. ReviewedKnow what a CSV export leaves outBefore
A CSV export does not include security questions, linked items, linked apps or custom fields.
How to export your data from the 1Password apps1Password Support. ReviewedDelete the plaintext export file when doneAfter
Exported files are not encrypted and are stored in plaintext. Don't email them or store them online, and delete them when you are done.
How to export your data from the 1Password apps1Password Support. Reviewed
At LastPass, when you join
Use a generic CSV if your manager isn't supportedBefore
If LastPass's on-screen import steps don't support your current password manager, you may be able to import a generic CSV file. Check first that your current manager can export to CSV.
How do I import stored data into LastPass using a generic CSV file?LastPass. ReviewedMatch your CSV columns to the LastPass templateDuring
Column titles must match LastPass's sample template. The columns are url, username, password, extra, name, grouping, fav and totp.
How do I import stored data into LastPass using a generic CSV file?LastPass. ReviewedUse passive import if your manager can't exportDuring
Run LastPass alongside your old password manager. Visit each site, let the old manager fill in your login, then add it to LastPass.
Then: everything else the switch affects
The steps above are what 1Password and LastPass say. Your full checklist adds the accounts, codes, payments and devices that depend on your password manager, in a safe order. It's built from your answers, in your browser.