My lavender plant was out most of summer in a pot, can i bring it in?

It depends on where you live. If you have hard frosts in your area, but want to leave it in the pot, I'd think about overwintering it in a shed or garage. However, if they're suitable for growing in your zone (i.e. wintering in your zone!), then they should be okay. You may want to shield them from the harshest winter storms.

https://ask.extension.org --- will depend on where you live -- many over-winter just fine ...

Get some Diatomaceous Earth and sprinkle it liberally all over the soil, blending it in as you go. A light overall dusting of the plant before you bring it inside will also help. It's all natural & non toxic, however be sure to NOT breathe it in.

Re-pot the lavender in the next size pot with drainage holes and fresh soil.spray the plant down with horticultral oil,bring inside and place in a bright location,water when dry to the touch

Leave it outside, cover with mulch or leaves. If you have a spot outside that gets the winter sun, move it there. It should be fine.

the link I provided will give you specific information for your area -- I think it may be too late to plant it this year -- but lavender is a hardy perennial in a lot of the country --