Lets vs Let's

[Josiah]

Lets (without an apostrophe) is the third-person singular form of the verb let, which means allow, permit, lease, or release.

Peggy lets the dog out the back door.



Let's (with an apostrophe) is the contracted form of let us

My little sister said, "Let's pretend the puppet family is going on a picnic."

 

[Warrigal]

Yep. That's how I understand it.

I use contractions a lot and always use the apostrophe.