All I need to use is lightroom. I guess Ive been using it for free. Can I Just pay for lightroom only. I already installed the updates
Please refer to the link Digital photography software | Download free Adobe Photoshop Lightroom CC trial for various purchasing options for Lightroom.
Hope this will help you.
If you wish to purchase Lightroom alone , you may buy LR 6 with serial number :
or if you wish you may purchase Creative Cloud Photography plan which includes Photoshop CC as well Lightroom CC for $9.99 per month.